Fisiología vegetal

Fotofisiología. Fotosíntesis. Pigmentos. Electrones. Protones. Metabolismo. Fotorrespiración. Nutrientes. Azufre. Giberelinas. Citoquininas

  • Enviado por: Alvaro Anduiza
  • Idioma: euskera
  • País: España España
  • 65 páginas
publicidad
publicidad

2º parcial

Tema 2 fotofisiología

La energía es necesaria para los organismos porque la utilizan para la síntesis de sus componentes.

Las plantas verdes la captan y la transforman en ð química, usada por los organismos vivos. Esto es la fotosíntesis q tiene lugar en los cloroplastos q tienen moléculas capaces de captar la ð y también todos los sistemas enzimáticos y cofactores necesarios para ensamblar es C inorgánico y otros elementos para formar la materia de los organismos.

La maquinaria eszimática esta en las hojas q son los órganos capacitados para captar la radiación, el CO2 atmosférico y al mismo modo están diseñados para evitar las perdidas de agua por la transpiración.

La fotosíntesis se da en dos fases: luminosa y oscura. Esto implica las reacciones en las q la ð luminosa mediante procesos de oxidorreducción por transferencia de e- se acumula en forma de ATP y poder reductor (NADPH) q lo reducen a carbohidratos.

El propósito de la fotosíntesis es un proceso mediante el q se aporta C inorgánico para aumentar la biomasa y se aporta ð para mantener esa biomasa.

La ð almacenada en azucares es liberada a través de la respiración.

La productividad depende del balance entre la fotosíntesis y la respiración teniendo en cuenta la distribución de compuestos de la fotosíntesis en los diferentes compartimentos celulares.

Hay plantas q han conseguido mediante variaciones fisiológicas adaptarse a distintos hábitat específicos.

La luz solar aporta ð para las plantas e información.

Desde un punto de vista energético, la energía solar mantiene la Tª para sintetizar los componentes celulares.

También la tiene como señal de las características del ambiente y la planta es capaz de regular sus movimientos. Desarrollar distintos procesos en la diferenciación, regula la floración, etc.

Todos estos aspectos se analizan mediante la fotobiología.

La fotosíntesis es una liberación de O2 y almacenamiento de poder reductor en compuestos azucarados. E un proceso de oxidorreducción.

El agua se oxida u los compuestos oxidados (CO2, sulfato, nitrato) se reducen.

Desde el punto de vista global aporta el imput energético necesario para la vida.

Biología de la radiación

Es el estudio de la radiación sobre los procesos biológicos.

Hay q distinguir entre radiaciones beneficiosas y nocivas. Solo una pequeña banda de radiación del visible es beneficiosa. (Hoja 1 Fig. 1) En el Sol se produce la fusión de 4H dando He y emisión de gran cantidad de ð dándose un aumento de Tª. Esta ð se trasloca a un[Author ID1: at Tue Aug 28 19:41:00 2001 ]una[Author ID1: at Tue Aug 28 19:41:00 2001] velocidad de 3*108m/sg y la naturaleza espectral es la expresada en la figura. De toda la radiación solo una pequeña parte de la energía es captada por la planta y utilizada par[Author ID1: at Fri Aug 31 02:32:00 2001 ]para[Author ID1: at Fri Aug 31 02:32:00 2001] llevar a cabo los procesos fotosintéticos.

(Hoja 2 Fig. 8.1) Respecto a la naturaleza de la radiación se propuso q la luz participa de características de onda y de partícula. La onda se caracteriza por una longitud q equivale a la distancia q existe entre dos picos de la onda, q se desplaza en la atm. Su frecuencia representa el numero de crestas q pasan ante un observador durante un periodo de tiempo determinado.

Fisiología vegetal

Una radiación electromagnética es también un[Author ID1: at Tue Aug 28 19:41:00 2001 ]una[Author ID1: at Tue Aug 28 19:41:00 2001] partícula denominada fotón, no Fisiología vegetal
se puede fraccionar para excitar dos moléculas distintas.

Solo existen diferencias energéticas entre distintos niveles dentro de la partícula.

Para pasar de un nivel energético a otro la energía solo puede ser aportada por un fotón.

La energía de un fotón depende de la frecuencia y de la constante de Planck.

Fisiología vegetal
Fisiología vegetal

Cuanto mayor es la longitud de onda menos energético es el fotón.

De toda la radiación solo la comprendida entre 200 - 900 nm es la utilizada por los organismos fotosintéticos.

Tres tipos de radiaciones:

Entre 200 nm y 900 nm es la radiación usada [Author ID1: at Thu Aug 30 16:55:00 2001]por los organismos fotosintéticos.[Author ID1: at Thu Aug 30 16:56:00 2001]

-->Entre 400[Author ID1: at Thu Aug 30 16:38:00 2001][Author ID1: at Thu Aug 30 16:39:00 2001] nm y 700 nm [Author ID1: at Thu Aug 30 16:38:00 2001]es la radiación fotosintéticamente activa, q es la absorbida por las plantas superiores[Author ID1: at Thu Aug 30 16:39:00 2001]-->[Author ID1: at Thu Aug 30 16:38:00 2001][Author ID1: at Thu Aug 30 16:38:00 2001]

En los sistemas biológicos las moléculas q absorben radiación son los pigmentos.

Se observa fluorescencia a partir de las moléculas de clorofila a y b, pero no a partir de carotenoides y xantofilas.

Fosforescencia :[Author ID1: at Thu Aug 30 16:40:00 2001] vida[Author ID1: at Thu Aug 30 18:11:00 2001] media[Author ID1: at Thu Aug 30 18:12:00 2001] de entre 10[Author ID1: at Thu Aug 30 18:11:00 2001]-4[Author ID1: at Thu Aug 30 18:12:00 2001] a 1 sg.,[Author ID1: at Thu Aug 30 18:12:00 2001] [Author ID1: at Thu Aug 30 16:40:00 2001]reemisión[Author ID1: at Thu Aug 30 16:44:00 2001] de la [Author ID1: at Thu Aug 30 16:40:00 2001]energía[Author ID1: at Thu Aug 30 16:44:00 2001] a una [Author ID1: at Thu Aug 30 16:40:00 2001]longitud[Author ID1: at Thu Aug 30 16:41:00 2001] [Author ID1: at Thu Aug 30 16:40:00 2001]de onda [Author ID1: at Thu Aug 30 16:41:00 2001]más[Author ID1: at Thu Aug 30 21:45:00 2001] larga. Se observa fluorescencia cuando la [Author ID1: at Thu Aug 30 16:41:00 2001]energía[Author ID1: at Thu Aug 30 16:44:00 2001] q se aplica [Author ID1: at Thu Aug 30 16:41:00 2001]-->sobrepasa[Author ID1: at Thu Aug 30 16:41:00 2001][Author ID1: at Thu Aug 30 16:43:00 2001] [Author ID1: at Thu Aug 30 16:41:00 2001]el punto de saturación de la [Author ID1: at Thu Aug 30 16:42:00 2001]fotosíntesis[Author ID1: at Thu Aug 30 16:44:00 2001], cuando disminuye la [CO[Author ID1: at Thu Aug 30 16:42:00 2001]2[Author ID1: at Thu Aug 30 16:42:00 2001]][Author ID1: at Thu Aug 30 16:42:00 2001], cuando se ilumina con luz blanca, radiación absorbida por [Author ID1: at Thu Aug 30 16:44:00 2001]carotenoides[Author ID1: at Thu Aug 30 16:45:00 2001] [Author ID1: at Thu Aug 30 16:44:00 2001]o con radiación absorbida por ficobilinas.[Author ID1: at Thu Aug 30 16:45:00 2001]-->[Author ID1: at Thu Aug 30 16:42:00 2001]

Procesos fisiológicos en plantas

  • 700 - 800 (rojo lejano)

  • Incremento altura, alargamiento entrenudos, fitocromo (rojo lejano 730 nm se inactiva), absorción bacterioclorofilas.

  • 610 - 700 nm (rojo)

  • Máxima actividad fotosintética, máxima absorción clorofilas (cloro. A 663 nm, cloro. B 644 nm), fitocromo (rojo 660 nm se activa).

  • 510 - 610 nm (verde - amarillo)

  • Mínima fotosíntesis, mínimo fotomorfogénesis (desarrollo estructural), absorción ficobilinas en algas rojas y cianofíceas.

  • 400 - 500 nm (azul)

  • Máxima fotosíntesis, máxima absorción clorofilas (cloro. A 420 nm, cloro. B 430 nm), absorción carotenoides (flavoprotei[Author ID1: at Sat Sep 8 18:49:00 2001 ]í[Author ID1: at Sat Sep 8 18:49:00 2001]nas y fitocromo), respuestas morfogenéticas (criptocromo), fototropismo.

  • 280- 400 nm (UV cercano)

  • Engrosamiento hojas, crecimiento compacto y enano (roseta), quemaduras solares.

  • menor de 280 nm (UV corto)

  • Radiaciones mutagénicas letales.

    Muchas de las respuestas desde la germinación a la floración están mediadas por el fitocromo. Están implicados en la germinación, reverdecimiento,[Author ID1: at Sat Sep 1 20:42:00 2001] adaptación del aparato fotosintético a la luz o sombra.

    Son complejos diméricos formados por un cromóforo y una proteína unida al cromóforo.

    Hay dos máximos de absorción a 660 y 730 nm.

    Cuando el fitocromo es capaz de absorber radiación a 660 nm, el cromóforo tiene configuración Cis inactiva (forma Pr). Cuando recibe la radiación se activa y pasa a la forma Pfr. Cuando absorbe radiación de 730 nm pasa a la forma inactiva Pr.

    Los espectros de absorción se solapan, es decir, hay una coexistencia de los dos tipos. Cuando recibe radiación de 660 nm el 88% esta activo y el 3% inactivo.

    Durante el día la mayor parte esta activa. Por la tarde tiende a inactivarse. El fitocromo tiene un receptor lo q conlleva la aparición de 2os mensajeros q activan proteinkinasa q fosforilan proteínas q activan genes en el núcleo.

    La inactivación es por procesos de proteolisis mediado por la colaboración de un[Author ID1: at Tue Aug 28 19:42:00 2001 ]una[Author ID1: at Tue Aug 28 19:42:00 2001] pequeña proteína denominada ubiquinona, q participa en procesos de degradación de proteínas. Actúa como un[Author ID1: at Tue Aug 28 19:43:00 2001 ]una[Author ID1: at Tue Aug 28 19:43:00 2001] especie de marcaje, va acompañada con gasto de ATP la unión de la ubiquinona a la proteína a degradar.

    Tema 3 fotosíntesis

    Las plantas verdes captan la energía solar transformándola en energía química mediante la fotosíntesis. En este proceso el agua y el CO2 se combinan para transformarlo en azucares simples y O2. estos[Author ID1: at Tue Aug 28 19:43:00 2001 ]Estos[Author ID1: at Tue Aug 28 19:43:00 2001] azucares se transforman en lípidos, proteínas, ac. nucleicos, etc.

    El proceso global se divide en 2 fases o 3 etapas:

    Primera etapa: captación de la radiación, absorción de luz y retención de la energía luminosa. Son los procesos fotosintéticos primarios.

    Segunda etapa: (Hoja 10 Fig. 1.1) la energía captada es convertida en energía química en forma de NADPH y ATP. Se crea un gradiente electroquímico de proteínas q se usa para la síntesis de ATP. Son los procesos fotoquímicos.

    Tercera etapa: proceso de estabilización y almacenamiento de la energía. Son procesos biológicos en los q se utiliza la energía almacenada para reducir el CO2 en azucares.

    En el sentido estricto es reducción y oxidación de CO2.

    La liberación de la energía de la fotosíntesis se realiza por el proceso contrario q es la respiración. Se da la oxidación de los azucares. Ambos procesos comparten características:

    • implican transporte de e- y fosforilación acoplada

    • se dan en orgánulos (cloroplastos y mitocondrias)

    [Author ID1: at Thu Aug 30 14:53:00 2001][Author ID1: at Thu Aug 30 14:52:00 2001 ]

    Experimento de Engelman (Hoja 12)[Author ID1: at Thu Aug 30 14:54:00 2001]

    -->Muestra la[Author ID1: at Thu Aug 30 14:54:00 2001][Author ID1: at Thu Aug 30 14:54:00 2001] [Author ID1: at Thu Aug 30 14:54:00 2001]relación[Author ID1: at Thu Aug 30 14:55:00 2001] entre el O[Author ID1: at Thu Aug 30 14:54:00 2001]2[Author ID1: at Thu Aug 30 14:55:00 2001] y el cloroplasto. [Author ID1: at Thu Aug 30 14:54:00 2001]Relación entre el CO[Author ID1: at Thu Aug 30 14:55:00 2001]2[Author ID1: at Thu Aug 30 14:55:00 2001] y las características de la luz.[Author ID1: at Thu Aug 30 14:55:00 2001]-->[Author ID1: at Thu Aug 30 14:54:00 2001]

    Mide el desprendimiento de O2 en el cloroplasto. Realiza el experimento con Chlorella en tres situaciones. En oscuridad y aplicaba focos de luz blanca, en el interior tení[Author ID1: at Thu Aug 30 14:53:00 2001]i[Author ID1: at Thu Aug 30 14:53:00 2001 ]a bacterias q se desarrollaban má[Author ID1: at Thu Aug 30 14:53:00 2001]a[Author ID1: at Thu Aug 30 14:53:00 2001 ]s con luz. Estas se concentraban en zonas donde se aplicaba la luz. Si iluminaba todo el medio la distribución era homogénea en el cloroplasto. Si iluminaba el medio con focos de luz roja y verde se daba acumulación en puntos del cloroplasto donde esta iluminado con luz roja. La luz verde no causa desprendimiento de O2.

    En el siglo XIX se establece la ecuación de ala fotosíntesis:

    CO2 + Agua + Luz + Planta verde === Materia orgánica + O2

    Desde el punto de vista bioquímico los primeros experimentos para determinar las primeras etapas de la fotosíntesis se llevaron a cabo con bacterias no fotosintéticas q utilizaban el CO2 como fuente de C. Cuando se utilizaban bacterias fotosintéticas estas utilizaban la energía radiante. Son anaerobias, la fuente reductora de H[Author ID1: at Fri Aug 31 11:53:00 2001 ]H+[Author ID1: at Fri Aug 31 11:53:00 2001] era SH2 y continuaban:

    CO2 + 2Sh2 === CH2O + H2O + 2s

    Había q determinar el origen del O2 Van Niel observó q lo q se liberaba en la fotosíntesis en las bacterias verde azuladas era el donador de H[Author ID1: at Fri Aug 31 11:53:00 2001 ]H+[Author ID1: at Fri Aug 31 11:53:00 2001]. Se liberaba el O2 proveniente del agua.

    Todos los análisis nos llevan a q las plantas usan la energía de la luz para oxidar el agua dando un agente reductor q posteriormente se usa para convertir el CO2 en CH- y se produce un oxidante q en realidad es un producto de desecho (O2) desprendido a la atmósfera.

    El desprendimiento de O2 forma parte de la fase luminosa y es independiente de la fase oscura.

    El proceso luminoso es un proceso de oxidorreducción donde los e- derivados de la fotosíntesis del agua son cedidos al CO2.

    La transferencia no es directa. Existen intermediarios q canalizan la transferencia del agua al CO2.

    En 1905 Blackman analizaba la respuesta de desprendimiento de O2 en función de la intensidad luminosa y [CO2].

    Había unas etapas en q el desprendimiento de O2 era proporcional a la intensidad luminosa. A una intensidad determinada no aumenta el desprendimiento.

    Con esto llega a la conclusión q hay dos fases: una donde las tasas de fotosíntesis dependen de la luz y otra donde dependen de procesos bioquímicos independientes de la luz y dependientes del CO2.

    Este tipo de respuesta explica por q la fotosíntesis se ve afectada por la Tª y venenos metabólicos.

    La fase luminosa es un proceso con reacciones biológicas no dependientes de la temperatura.

    La fase oscura depende de la Tª dentro de los márgenes fisiológicos.

    La aplicación de venenos limita las tasas fotosintéticas sobre todo en la fase oscura.

    Fisiología vegetal
    [Author ID1: at Thu Aug 30 17:01:00 2001]Esta teoría fue demostrada por Emerson con el alga Chlorella. Daba lo mismo aplicar luz continua o dar destellos de luz de distintas intensidades. A medida q aumenta la intensidad del destello aumenta la tasa de desprendimiento llegando a un momento en q por mucho q aumente la intensidad el desprendimiento de O2 no aumenta. Se da saturación luminosa. Esto ocurre con los destellos.

    Llevaron a cabo experimentos de cómo influía el periodo entre dos destellos en el desprendimiento de O2. Si el periodo de oscuridad aumenta el desprendimiento aumenta.

    Para que se consuman los productos de la fase luminosa se necesita un periodo de por lo menos 0.06 segundos.

    Para reducir un mol de CO2 a CH- se necesita la fotolisis de 2 H2O para obtener los 4 e- y 4 H+ requeridos.

    Para pasar 1 e- del par O2 al NADPH se necesitan dos fotones. Para producir la transferencia de los 4 e- se requieren como mínimo 8 fotones.

    El -->rendimiento [Author ID1: at Sat Sep 1 16:55:00 2001 ][Author ID1: at Sat Sep 1 16:55:00 2001]-->re[Author ID1: at Sat Sep 1 16:55:00 2001][Author ID1: at Sat Sep 1 16:55:00 2001]querimiento [Author ID1: at Sat Sep 1 17:01:00 2001]c[Author ID1: at Sat Sep 1 17:05:00 2001]-->q[Author ID1: at Sat Sep 1 17:05:00 2001 ][Author ID1: at Sat Sep 1 16:55:00 2001]-->uántico[Author ID1: at Sat Sep 1 16:55:00 2001] es la cantidad de energía q se precisan[Author ID1: at Sat Sep 1 17:01:00 2001 ] para fijar una molécula de CO2 o desprendimiento de un O2.[Author ID0: at ]

    El [Author ID1: at Sat Sep 1 17:01:00 2001]-->rendimiento cu[Author ID1: at Sat Sep 1 17:02:00 2001][Author ID1: at Sat Sep 1 17:04:00 2001]á[Author ID1: at Sat Sep 1 17:05:00 2001]-->ntico[Author ID1: at Sat Sep 1 17:02:00 2001][Author ID1: at Sat Sep 1 17:04:00 2001] es la cantidad de producto necesario ([Author ID1: at Sat Sep 1 17:02:00 2001]Fijación[Author ID1: at Sat Sep 1 17:03:00 2001] [Author ID1: at Sat Sep 1 17:02:00 2001]de CO[Author ID1: at Sat Sep 1 17:03:00 2001]2 [Author ID1: at Sat Sep 1 17:03:00 2001] o desprendimiento de O[Author ID1: at Sat Sep 1 17:03:00 2001]2[Author ID1: at Sat Sep 1 17:03:00 2001])[Author ID1: at Sat Sep 1 17:03:00 2001] para absorber un fotón. Es el inverso del requerimiento cu[Author ID1: at Sat Sep 1 17:04:00 2001]á[Author ID1: at Sat Sep 1 17:05:00 2001]ntico.[Author ID1: at Sat Sep 1 17:04:00 2001][Author ID0: at ]

    El [Author ID1: at Sat Sep 1 17:05:00 2001]-->cuantosoma[Author ID1: at Sat Sep 1 17:05:00 2001][Author ID1: at Sat Sep 1 17:06:00 2001] es la unidad funcional [Author ID1: at Sat Sep 1 17:05:00 2001]mínima[Author ID1: at Sat Sep 1 17:06:00 2001] para q se de desprendimiento de O[Author ID1: at Sat Sep 1 17:05:00 2001]2[Author ID1: at Sat Sep 1 17:06:00 2001] del fotosistema. No existe como tal.[Author ID1: at Sat Sep 1 17:06:00 2001]-->[Author ID1: at Sat Sep 1 17:06:00 2001]

    Para absorber un fotón se necesitan entre 240 - 300 clorofilas.

    Tema 4 pigmentos fotosintéticos

    (Hoja 13) Las células fotosintéticas contienen al menos un tipo de clorofila capaz de absorber radiación del visible.

    La mayoría de las células tienen carotenoides y las ficobilinas. Estas son azules o rojas y los carotenoides son amarillos o naranjas. A estos se les denomina pigmentos accesorios (la radiación captada por ellos no se usa directamente en la fotosíntesis sino q es transferida a la clorofila.

    Las ficobilinas son hidrosolubles y carotenos y clorofilas insolubles en agua (son solubles en disolventes orgánicos).

    Las clorofilas son pigmentos fotosintéticos verdes con 4 anillos tetrapirrólicos con diversos sustituyentes unidos a los C de los anillos.

    Los N de los pirroles tienen e- no compartidos q sirven para formar enlaces de coordinación con el Mg2+ formando una estructura prácticamente plana. Unido mediante enlace ester a través de un residuo propiónico q pende de C-7 del pirrol 4, hay un largo brazo con estructura terpenoide hidrófobo q es el resto del fitol.

    Cuando por hidrólisis se pierde el fitol, la molécula q queda es la clorofilida.

    La [Author ID1: at Mon Sep 10 21:55:00 2001]Si se elimina el Mg[Author ID1: at Mon Sep 10 21:54:00 2001 ]2+[Author ID1: at Mon Sep 10 21:54:00 2001 ] por tratamiento ácido la molécula q queda es la [Author ID1: at Mon Sep 10 21:54:00 2001 ]feofitina[Author ID1: at Mon Sep 10 21:55:00 2001 ]feofitina, [Author ID1: at Mon Sep 10 21:55:00 2001] [Author ID1: at Mon Sep 10 21:55:00 2001 ]q es el aceptor primario de e- del PS II, es una molécula de clorofila-a modificada, en la q dos [Author ID1: at Mon Sep 10 21:55:00 2001]átomos[Author ID1: at Mon Sep 10 21:58:00 2001] de H han reemplazado al Mg[Author ID1: at Mon Sep 10 21:55:00 2001]2+[Author ID1: at Mon Sep 10 21:56:00 2001] central.[Author ID1: at Mon Sep 10 21:56:00 2001].[Author ID1: at Mon Sep 10 21:55:00 2001 ]

    Tanto en el núcleo central como en el fitol hay un doble enlace conjugado. Esta característica es lo[Author ID1: at Mon Aug 27 14:45:00 2001 ]la[Author ID1: at Mon Aug 27 14:45:00 2001] q permite la captación de la luz. [Author ID1: at Mon Aug 27 14:43:00 2001]Las clorofilas en [Author ID1: at Mon Aug 27 14:48:00 2001]éter[Author ID1: at Mon Aug 27 14:51:00 2001] de [Author ID1: at Mon Aug 27 14:48:00 2001]petróleo[Author ID1: at Mon Aug 27 14:51:00 2001] en el espectro de absorción [Author ID1: at Mon Aug 27 14:48:00 2001]presentan[Author ID1: at Tue Aug 28 19:44:00 2001] un máximo en la clorofila b a 644 [Author ID1: at Mon Aug 27 14:48:00 2001]-[Author ID1: at Mon Aug 27 14:49:00 2001] 430 [Author ID1: at Mon Aug 27 14:48:00 2001]nm y en la clorofila a 663 - 420 nm. Variando [Author ID1: at Mon Aug 27 14:49:00 2001]el disolvente en q han sido [Author ID1: at Mon Aug 27 14:50:00 2001]extraídas[Author ID1: at Mon Aug 27 14:51:00 2001] estas[Author ID1: at Mon Aug 27 14:50:00 2001] [Author ID1: at Mon Aug 27 14:51:00 2001]medidas [Author ID1: at Mon Aug 27 14:50:00 2001]varían[Author ID1: at Mon Aug 27 14:51:00 2001].[Author ID1: at Mon Aug 27 14:50:00 2001] [Author ID1: at Mon Aug 27 14:51:00 2001][Author ID1: at Mon Aug 27 14:44:00 2001 ]

    T[Author ID1: at Mon Aug 27 14:51:00 2001]odos los organismos [Author ID1: at Mon Aug 27 14:50:00 2001]fotosintéticos tienen clorofila a y las plantas verdes tien[Author ID1: at Mon Aug 27 14:51:00 2001]en entre la clorofila a y la b [Author ID1: at Mon Aug 27 14:52:00 2001]una[Author ID1: at Tue Aug 28 19:44:00 2001] relación de 2/3. se encuentran en los clorop[Author ID1: at Mon Aug 27 14:52:00 2001]lastos. Las algas pardas diatomeas tienen la c u las rojas tienen las clorofilas d.[Author ID1: at Mon Aug 27 14:53:00 2001]

    En la [Author ID1: at Mon Aug 27 14:56:00 2001]mayoría[Author ID1: at Mon Aug 27 15:07:00 2001] de las bacterias fotosintéticas el pigmento principal es la bacterioclorofila [Author ID1: at Mon Aug 27 14:56:00 2001]a,[Author ID1: at Tue Aug 28 19:45:00 2001] si bien algunas del genero Rhodopseudomonas tien[Author ID1: at Mon Aug 27 14:56:00 2001]en bacterioclorofila d.[Author ID1: at Mon Aug 27 14:57:00 2001][Author ID0: at ]

    Las bacterias [Author ID1: at Mon Aug 27 14:58:00 2001]verde sulfúreas[Author ID1: at Mon Aug 27 15:07:00 2001] tienen las clorofilas de clorobiun. [Author ID1: at Mon Aug 27 14:58:00 2001]Es [Author ID1: at Mon Aug 27 14:59:00 2001]una[Author ID1: at Tue Aug 28 19:45:00 2001] familia de clorofilas.[Author ID0: at ]

    [Author ID0: at ]

    En la captación participan los carotenoides. Son poliisoprenoides q pueden ser de dos tipos[Author ID1: at Mon Aug 27 14:59:00 2001]: carotenoides constituidos por C e [Author ID1: at Mon Aug 27 15:01:00 2001]H[Author ID1: at Fri Aug 31 11:54:00 2001] y xantofila[Author ID1: at Mon Aug 27 15:01:00 2001]s q [Author ID1: at Mon Aug 27 15:02:00 2001]tienen[Author ID1: at Mon Aug 27 15:08:00 2001] C, O e H. Son tetrapirroles con dobles enlaces conjugados.[Author ID1: at Mon Aug 27 15:02:00 2001][Author ID0: at ]

    Máxima absorción a 450 - 490 nm por lo q apoyan a aumentar el es[Author ID1: at Mon Aug 27 15:03:00 2001]pectro de absorción de organismos q los poseen. [Author ID1: at Mon Aug 27 15:04:00 2001]Están[Author ID1: at Mon Aug 27 15:08:00 2001] en los tilac[Author ID1: at Mon Aug 27 15:04:00 2001]o[Author ID1: at Mon Aug 27 15:08:00 2001]ides[Author ID1: at Mon Aug 27 15:04:00 2001] asociados a [Author ID1: at Mon Aug 27 15:05:00 2001]proteínas[Author ID1: at Mon Aug 27 15:08:00 2001] y clorofila y también en la envuelta del cloroplasto.[Author ID0: at ]

    Tienen papel como fotoprotectores [Author ID1: at Mon Aug 27 15:05:00 2001]además[Author ID1: at Mon Aug 27 15:08:00 2001] de [Author ID1: at Mon Aug 27 15:05:00 2001]captación[Author ID1: at Mon Aug 27 15:06:00 2001] [Author ID1: at Mon Aug 27 15:05:00 2001]de radiación y pigmentos [Author ID1: at Mon Aug 27 15:06:00 2001]accesorios[Author ID1: at Mon Aug 27 15:08:00 2001].[Author ID1: at Mon Aug 27 15:06:00 2001] [Author ID0: at ]

    Las ficobilinas son pigmentos de algas, normalmente tetrapirroles abiertos.[Author ID1: at Mon Aug 27 15:18:00 2001]

    [Author ID1: at Mon Aug 27 15:19:00 2001]

    Biosíntesis de clorofilas[Author ID1: at Mon Aug 27 15:19:00 2001]

    Se sintetizan a [Author ID1: at Mon Aug 27 15:19:00 2001]partir[Author ID1: at Mon Aug 27 18:51:00 2001] de glutamato. Mediante una serie de etapas se forma el tetrapirrol, [Author ID1: at Mon Aug 27 15:19:00 2001]luego[Author ID1: at Mon Aug 27 18:51:00 2001] se incluye el magnesio llegando a formarse al final la clorofila.[Author ID1: at Mon Aug 27 15:19:00 2001]

    (Hoja 15)[Author ID1: at Mon Aug 27 15:21:00 2001] Partimos de glutamato q es activado al uniese al RNAt con gasto de ATP y el Mg[Author ID1: at Mon Aug 27 15:21:00 2001]2+[Author ID1: at Mon Aug 27 15:22:00 2001] como cofactor. Seguidamente es reducido con gasto de NADH [Author ID1: at Mon Aug 27 15:22:00 2001]para[Author ID1: at Fri Aug 31 02:33:00 2001] dar glutamatosemialdehido. A partir de [Author ID1: at Mon Aug 27 15:22:00 2001]aquí[Author ID1: at Mon Aug 27 15:23:00 2001] [Author ID1: at Mon Aug 27 15:22:00 2001]se obtiene el[Author ID1: at Mon Aug 27 15:23:00 2001] ac.[Author ID1: at Mon Aug 27 15:30:00 2001] [Author ID1: at Mon Aug 27 15:23:00 2001][Author ID1: at Mon Aug 27 15:29:00 2001]- aninolevulínico[Author ID1: at Mon Aug 27 15:30:00 2001], q es el inicio de la síntesis. [Author ID0: at ]

    A partir de dos moléculas de - aminolevulínico por [Author ID1: at Mon Aug 27 15:31:00 2001]condensación[Author ID1: at Mon Aug 27 15:32:00 2001] [Author ID1: at Mon Aug 27 15:31:00 2001]y [Author ID1: at Mon Aug 27 15:32:00 2001]deshidrogenación[Author ID1: at Mon Aug 27 15:36:00 2001] se forma el[Author ID1: at Mon Aug 27 15:32:00 2001] [Author ID1: at Mon Aug 27 15:36:00 2001]porfobilinógeno (PBG) q es el pirrol [Author ID1: at Mon Aug 27 15:32:00 2001]liberándose[Author ID1: at Mon Aug 27 15:33:00 2001] [Author ID1: at Mon Aug 27 15:32:00 2001]2 H[Author ID1: at Mon Aug 27 15:33:00 2001]2[Author ID1: at Mon Aug 27 15:33:00 2001]O.[Author ID0: at ]

    4 [Author ID1: at Mon Aug 27 15:33:00 2001]moléculas[Author ID1: at Mon Aug 27 15:36:00 2001] de p[Author ID1: at Mon Aug 27 15:33:00 2001]o[Author ID1: at Mon Aug 27 15:36:00 2001]rfobilinógeno forman el tetrapirrol[Author ID1: at Mon Aug 27 15:33:00 2001] catalizadas po[Author ID1: at Mon Aug 27 15:33:00 2001]r do enzimas, la primera cataliza la [Author ID1: at Mon Aug 27 15:34:00 2001]unión[Author ID1: at Mon Aug 27 15:37:00 2001] de los pirroles con liberación de 2 amonios. L[Author ID1: at Mon Aug 27 15:34:00 2001]a segunda canaliza la permutación de los radicales del 4º pirro[Author ID1: at Mon Aug 27 15:35:00 2001]l.[Author ID1: at Mon Aug 27 15:36:00 2001][Author ID0: at ]

    El uroporfirinógeno se descarboxila 4 veces dando el coproporfirin[Author ID1: at Mon Aug 27 19:07:00 2001]ó[Author ID1: at Mon Aug 27 19:13:00 2001]geno[Author ID1: at Mon Aug 27 19:07:00 2001] III, el CO[Author ID1: at Mon Aug 27 19:11:00 2001]2[Author ID1: at Mon Aug 27 19:11:00 2001] [Author ID1: at Mon Aug 27 19:15:00 2001]q se libera proviene de los acetilos. La siguiente etapa es un descarboxilación oxidativa [Author ID1: at Mon Aug 27 19:14:00 2001]transformándose[Author ID1: at Mon Aug 27 19:15:00 2001] [Author ID1: at Mon Aug 27 19:14:00 2001]en protoporfirinogeno IX.[Author ID1: at Mon Aug 27 19:15:00 2001]

    Deshidrogenación[Author ID1: at Mon Aug 27 19:16:00 2001] [Author ID1: at Mon Aug 27 19:15:00 2001]transformándose en protoporfirina IX. Es el punto de bifurcación en la síntesis de ferroporfirinas, clorofila...[Author ID1: at Mon Aug 27 19:16:00 2001]

    Incorporación de Mg[Author ID1: at Mon Aug 27 19:17:00 2001]2+[Author ID1: at Mon Aug 27 19:17:00 2001] por la Mg[Author ID1: at Mon Aug 27 19:17:00 2001]2+[Author ID1: at Mon Aug 27 19:17:00 2001] quelasa con gasto de ATP formando un enlace de [Author ID1: at Mon Aug 27 19:17:00 2001]coordinación[Author ID1: at Mon Aug 27 19:18:00 2001] [Author ID1: at Mon Aug 27 19:17:00 2001]con los N.[Author ID1: at Mon Aug 27 19:18:00 2001][Author ID0: at ]

    Incorporación de metilo en el radical [Author ID1: at Mon Aug 27 19:21:00 2001]propílico[Author ID1: at Mon Aug 27 19:22:00 2001] ligado al C[Author ID1: at Mon Aug 27 19:21:00 2001]6[Author ID1: at Mon Aug 27 19:21:00 2001]. [Author ID1: at Mon Aug 27 19:21:00 2001]A[Author ID1: at Tue Aug 28 19:46:00 2001] partir de esta molécula en las siguientes etapas se forma el 5º anillo.[Author ID1: at Mon Aug 27 19:21:00 2001][Author ID0: at ]

    Las siguientes etapas son hidrogenaciones. [Author ID1: at Mon Aug 27 19:22:00 2001]En la siguiente etapa interviene la luz, un destello de 650 nm en la q se añaden 2 H[Author ID1: at Mon Aug 27 19:23:00 2001]+[Author ID1: at Mon Aug 27 19:24:00 2001]. La ultima etapa es la esterificaci[Author ID1: at Mon Aug 27 19:24:00 2001]ó[Author ID1: at Mon Aug 27 19:27:00 2001]n del fitol para dar la clorofila.[Author ID0: at ]

    La luz [Author ID1: at Mon Aug 27 19:24:00 2001]además[Author ID1: at Mon Aug 27 19:26:00 2001] de controlar la [Author ID1: at Mon Aug 27 19:24:00 2001]adición[Author ID1: at Mon Aug 27 19:26:00 2001] de 2H tiene q regular las pri[Author ID1: at Mon Aug 27 19:24:00 2001]mera 3 etapas, para la [Author ID1: at Mon Aug 27 19:24:00 2001]formación[Author ID1: at Mon Aug 27 19:25:00 2001] [Author ID1: at Mon Aug 27 19:24:00 2001]del[Author ID1: at Mon Aug 27 19:25:00 2001] - aminolevulínico[Author ID1: at Mon Aug 27 19:26:00 2001].[Author ID0: at ]

    Se catalizan en cloroplastos mediante enzimas sintetizados por ri[Author ID1: at Mon Aug 27 19:27:00 2001]bosomas codificados por el genoma [Author ID1: at Mon Aug 27 19:28:00 2001]nuclear[Author ID1: at Mon Aug 27 19:29:00 2001].[Author ID0: at ]

    El Fe también participa en el control de la síntesis de la clorofila[Author ID1: at Mon Aug 27 19:28:00 2001].[Author ID0: at ]

    El exceso [Author ID1: at Mon Aug 27 19:29:00 2001]inhibe[Author ID1: at Mon Aug 27 20:01:00 2001] la s[Author ID1: at Mon Aug 27 19:29:00 2001]íntesis de clorofila porque tira a la [Author ID1: at Mon Aug 27 19:29:00 2001]síntesis[Author ID1: at Mon Aug 27 19:30:00 2001] [Author ID1: at Mon Aug 27 19:29:00 2001]de grupos hemo y no hacia la síntesis de clorofila. La regulación del sistema viene determinado por los niveles de [Author ID1: at Mon Aug 27 19:30:00 2001]protoclorofilida-[Author ID1: at Thu Aug 30 18:38:00 2001]a:[Author ID1: at Mon Aug 27 19:30:00 2001]

    [Author ID1: at Mon Aug 27 19:31:00 2001]

    Síntesis de [Author ID1: at Mon Aug 27 19:31:00 2001]carotenoides [Author ID1: at Mon Aug 27 19:32:00 2001](Hoja 16 [Author ID1: at Mon Aug 27 19:31:00 2001]Fig.[Author ID1: at Mon Aug 27 22:09:00 2001] 11.9)[Author ID1: at Mon Aug 27 19:31:00 2001]

    Se inicia con [Author ID1: at Mon Aug 27 19:32:00 2001]Ac. CoA condensándose dos moléculas para dar acetoacetil CoA.[Author ID1: at Mon Aug 27 19:33:00 2001] A continuación se incorpora otro Ac. CoA para dar [Author ID1: at Mon Aug 27 19:34:00 2001]-hidroxi--metilglutaril-CoA q se reduce a mevalonico mediante un enzima[Author ID1: at Mon Aug 27 19:35:00 2001] dependiente de NADP.[Author ID1: at Mon Aug 27 19:38:00 2001][Author ID0: at ]

    Se fosforilan y descarboxilan para obtener los intermediarios de [Author ID1: at Mon Aug 27 19:39:00 2001]5C para la síntesis del resto de terpenoides.[Author ID1: at Mon Aug 27 19:40:00 2001][Author ID0: at ]

    Hay otra ruta q parte de ac. pir[Author ID1: at Mon Aug 27 19:43:00 2001]ú[Author ID1: at Mon Aug 27 20:00:00 2001]vicos y 3PGA.[Author ID1: at Mon Aug 27 19:43:00 2001]

    [Author ID1: at Mon Aug 27 19:45:00 2001]

    [Author ID1: at Mon Aug 27 19:45:00 2001]

    T[Author ID1: at Mon Aug 27 19:45:00 2001]ema 5 aparato fotosintético[Author ID1: at Mon Aug 27 19:45:00 2001]

    [Author ID1: at Mon Aug 27 19:45:00 2001]

    Los [Author ID1: at Mon Aug 27 19:46:00 2001]experimentos[Author ID1: at Mon Aug 27 20:00:00 2001] llevados a cabo por Engelman y Von Sach determinaban la [Author ID1: at Mon Aug 27 19:46:00 2001]relación[Author ID1: at Mon Aug 27 20:00:00 2001] de diferentes [Author ID1: at Mon Aug 27 19:46:00 2001]orgánulos[Author ID1: at Mon Aug 27 20:00:00 2001]. [Author ID1: at Mon Aug 27 19:46:00 2001]El desprendimiento de O[Author ID1: at Mon Aug 27 19:47:00 2001]2[Author ID1: at Mon Aug 27 19:47:00 2001] y formación de [Author ID1: at Mon Aug 27 19:47:00 2001]almidón[Author ID1: at Mon Aug 27 20:00:00 2001] en estos [Author ID1: at Mon Aug 27 19:47:00 2001]orgánulos[Author ID1: at Mon Aug 27 20:00:00 2001] q son los cloroplastos. [Author ID1: at Mon Aug 27 19:47:00 2001]Son [Author ID1: at Mon Aug 27 19:48:00 2001]orgánulos[Author ID1: at Mon Aug 27 20:00:00 2001] subcelulares en la [Author ID1: at Mon Aug 27 19:48:00 2001]mayoría[Author ID1: at Mon Aug 27 20:00:00 2001] de células de tejidos fotosintéticos de tamaño de 5 [Author ID1: at Mon Aug 27 19:48:00 2001]-[Author ID1: at Mon Aug 27 19:49:00 2001] 10 [Author ID1: at Mon Aug 27 19:48:00 2001]m de diámetro. Dado [Author ID1: at Mon Aug 27 19:49:00 2001]su color verde y gran tamaño se pueden ver con microscopio [Author ID1: at Mon Aug 27 19:50:00 2001]óptico[Author ID1: at Mon Aug 27 20:00:00 2001].[Author ID0: at ]

    En algas unicelulares hay un [Author ID1: at Mon Aug 27 19:50:00 2001]único[Author ID1: at Mon Aug 27 19:59:00 2001] cloroplasto. [Author ID1: at Mon Aug 27 19:50:00 2001]Lo [Author ID1: at Mon Aug 27 19:51:00 2001]normal[Author ID1: at Mon Aug 27 20:00:00 2001] es 20-50 cloroplastos por [Author ID1: at Mon Aug 27 19:51:00 2001]célula[Author ID1: at Mon Aug 27 20:00:00 2001] fotosintética.[Author ID0: at ]

    Difieren de forma y tamaño en [Author ID1: at Mon Aug 27 19:51:00 2001]las distintas plantas. Son carac[Author ID1: at Mon Aug 27 19:52:00 2001]terísticos de organismos fotosintéticos eucariotas. Procariotas y algas [Author ID1: at Mon Aug 27 19:52:00 2001]verde azuladas[Author ID1: at Mon Aug 27 20:00:00 2001] poseen verdaderos clorop[Author ID1: at Mon Aug 27 19:52:00 2001]lastos. Todos los [Author ID1: at Mon Aug 27 19:53:00 2001]orgánulos[Author ID1: at Mon Aug 27 20:00:00 2001] tienen un sistema laminar de membrana donde se da la captación y [Author ID1: at Mon Aug 27 19:53:00 2001]transformación de [Author ID1: at Mon Aug 27 19:54:00 2001]energía[Author ID1: at Mon Aug 27 20:00:00 2001].[Author ID0: at ]

    En los organismos fotosintéticos eucariotas estas estructuras laminares [Author ID1: at Mon Aug 27 19:54:00 2001]están[Author ID1: at Mon Aug 27 19:59:00 2001] separadas del citoplasma por una cubierta membranosa.[Author ID1: at Mon Aug 27 19:54:00 2001][Author ID0: at ]

    Eubacterias fotosintéticas no tienen esta cubierta. Los sistemas membranosos se unen en estructuras discretas denominadas [Author ID1: at Mon Aug 27 19:55:00 2001]cromatóforos[Author ID1: at Mon Aug 27 19:59:00 2001].[Author ID0: at ]

    En cianofíceas las membranas se [Author ID1: at Mon Aug 27 19:56:00 2001]dan por plegamientos y ramificación de la membrana externa.[Author ID0: at ]

    Los cloroplastos son una subclase de [Author ID1: at Mon Aug 27 20:09:00 2001]orgánulos[Author ID1: at Mon Aug 27 20:11:00 2001] [Author ID1: at Mon Aug 27 20:09:00 2001]subcelulares[Author ID1: at Mon Aug 27 20:10:00 2001] [Author ID1: at Mon Aug 27 20:09:00 2001]llamados plastidios q [Author ID1: at Mon Aug 27 20:10:00 2001]están[Author ID1: at Mon Aug 27 20:11:00 2001] en todas las células [Author ID1: at Mon Aug 27 20:10:00 2001]fotosintéticas[Author ID1: at Mon Aug 27 20:11:00 2001].[Author ID1: at Mon Aug 27 20:10:00 2001]

    -->(Hoja 18)[Author ID1: at Mon Aug 27 20:10:00 2001][Author ID1: at Mon Aug 27 20:11:00 2001] Desde el punto de vista de estructura microscópica los cloroplastos [Author ID1: at Mon Aug 27 20:11:00 2001]están[Author ID1: at Mon Aug 27 20:17:00 2001] constituidos por lamelas q se disponen paralelas al eje[Author ID1: at Mon Aug 27 20:11:00 2001] mayor de la estructura del cloroplasto. Estas lamelas se [Author ID1: at Mon Aug 27 20:12:00 2001]sitúan[Author ID1: at Mon Aug 27 20:17:00 2001] agrupad[Author ID1: at Mon Aug 27 20:12:00 2001]as de modo paralelo en forma de saco dejando un espacio entre ellos denominado tilacoides.[Author ID1: at Mon Aug 27 20:13:00 2001]

    Están[Author ID1: at Mon Aug 27 20:16:00 2001] [Author ID1: at Mon Aug 27 20:13:00 2001]embebidos en la matriz q es el estroma. Varios tilacoides se unen formando [Author ID1: at Mon Aug 27 20:14:00 2001]una[Author ID1: at Tue Aug 28 19:52:00 2001] agrupación de entre 10- 100 q reciben el nombre de grana. [Author ID1: at Mon Aug 27 20:14:00 2001]Estos, [Author ID1: at Mon Aug 27 20:15:00 2001]están[Author ID1: at Mon Aug 27 20:17:00 2001] conectados por lamas o laminas [Author ID1: at Mon Aug 27 20:15:00 2001]más[Author ID1: at Tue Aug 28 19:52:00 2001] grandes q se expanden por e[Author ID1: at Mon Aug 27 20:15:00 2001]l citoplasma del cloroplasto.[Author ID1: at Mon Aug 27 20:16:00 2001] El [Author ID1: at Mon Aug 27 20:19:00 2001]tamaño de los grana esta entre 0.2-0.3 [Author ID1: at Mon Aug 27 20:21:00 2001]m, habien[Author ID1: at Mon Aug 27 20:21:00 2001]do unos 50 por cloroplasto.[Author ID1: at Mon Aug 27 20:22:00 2001]

    (Hoja[Author ID1: at Mon Aug 27 20:22:00 2001] 19)[Author ID1: at Mon Aug 27 20:23:00 2001] Los tilacoides encierran un espacio q es el lumen del cloroplasto. Las membranas tienen permeabilidad selectiva. [Author ID1: at Mon Aug 27 20:24:00 2001]La selectividad la [Author ID1: at Mon Aug 27 20:25:00 2001]determina[Author ID1: at Mon Aug 27 20:28:00 2001] la membrana interna. La externa en m[Author ID1: at Mon Aug 27 20:25:00 2001]á[Author ID1: at Sun Sep 2 17:06:00 2001]s o menos permeable. Entran a[Author ID1: at Mon Aug 27 20:25:00 2001]l espacio intermembranal por los poros y para pasar la membrana interna necesitan transportadores.[Author ID1: at Mon Aug 27 20:25:00 2001]

    Del exterior al interior[Author ID1: at Mon Aug 27 20:26:00 2001] [Author ID1: at Mon Aug 27 20:29:00 2001]hay una doble membrana, estroma y una serie de laminillas dispuestas en agrupaciones o libres y dentro de los sacos el lumen.[Author ID1: at Mon Aug 27 20:30:00 2001]

    Con frecuencia los cloroplastos de [Author ID1: at Mon Aug 27 20:31:00 2001]muchas[Author ID1: at Mon Aug 27 20:32:00 2001] algas presentan una acumulación de [Author ID1: at Mon Aug 27 20:31:00 2001]almidón[Author ID1: at Mon Aug 27 20:32:00 2001] q se denomina piren[Author ID1: at Mon Aug 27 20:31:00 2001]o[Author ID1: at Mon Aug 27 20:32:00 2001]ide.[Author ID1: at Mon Aug 27 20:31:00 2001] En plantas superiores [Author ID1: at Mon Aug 27 20:32:00 2001]también[Author ID1: at Mon Aug 27 20:33:00 2001] [Author ID1: at Mon Aug 27 20:32:00 2001]hay acumulación de almidón q se acumula de día y se degrada de noche.[Author ID0: at ]

    [Author ID1: at Mon Aug 27 20:33:00 2001]

    Membrana cloroplástica[Author ID1: at Mon Aug 27 20:34:00 2001]

    No [Author ID1: at Mon Aug 27 20:34:00 2001]deriva[Author ID1: at Mon Aug 27 20:41:00 2001] del retículo endoplasmatico. Su biogénesis es propia, es decir, [Author ID1: at Mon Aug 27 20:34:00 2001]están[Author ID1: at Mon Aug 27 20:41:00 2001] [Author ID1: at Mon Aug 27 20:34:00 2001]reguladas[Author ID1: at Mon Aug 27 20:41:00 2001] por su propio genoma. [Author ID1: at Mon Aug 27 20:34:00 2001]Sin clorofila.[Author ID0: at ]

    Contiene carotenoides q no participan en la captación de la [Author ID1: at Mon Aug 27 20:35:00 2001]radiación[Author ID1: at Mon Aug 27 20:36:00 2001].[Author ID1: at Mon Aug 27 20:35:00 2001][Author ID0: at ]

    Ricos en [Author ID1: at Mon Aug 27 20:36:00 2001]sulfolípidos[Author ID1: at Tue Aug 28 19:47:00 2001] y galactol[Author ID1: at Mon Aug 27 20:36:00 2001]í[Author ID1: at Tue Aug 28 19:48:00 2001]pidos. [Author ID1: at Mon Aug 27 20:36:00 2001]No tiene fosfatidilcolina ni fosfatidiletanolamina.[Author ID1: at Mon Aug 27 20:40:00 2001] [Author ID1: at Mon Aug 27 20:41:00 2001]Posee quinonas. Es el lugar de síntesis de los componentes de membrana (fosfol[Author ID1: at Mon Aug 27 20:38:00 2001]í[Author ID1: at Tue Aug 28 19:48:00 2001]pidos, [Author ID1: at Mon Aug 27 20:38:00 2001]carotenoides[Author ID1: at Mon Aug 27 20:39:00 2001],[Author ID1: at Mon Aug 27 20:38:00 2001] flavonoides, terpenos, [Author ID1: at Mon Aug 27 20:39:00 2001]quinonas,[Author ID1: at Tue Aug 28 19:53:00 2001] ac. [Author ID1: at Mon Aug 27 20:39:00 2001]grasos)[Author ID1: at Mon Aug 27 20:40:00 2001].[Author ID0: at ]

    [Author ID1: at Mon Aug 27 20:45:00 2001]

    Membrana del Tilacoide[Author ID1: at Mon Aug 27 20:45:00 2001]

    -->Po[Author ID1: at Mon Aug 27 20:45:00 2001][Author ID1: at Mon Aug 27 20:46:00 2001]ca fosfatidilcolina, no hay fosfatidiletanolamina. Ricos en galctol[Author ID1: at Mon Aug 27 20:46:00 2001]í[Author ID1: at Mon Aug 27 20:52:00 2001]pidos y sulfolípidos. Ricas en ac grasos muy insaturados q le dan gran fluidez a la membrana [Author ID1: at Mon Aug 27 20:46:00 2001]favoreciendo[Author ID1: at Mon Aug 27 20:47:00 2001] [Author ID1: at Mon Aug 27 20:46:00 2001]el desplazamiento de transportadores de e[Author ID1: at Mon Aug 27 20:47:00 2001]-[Author ID1: at Mon Aug 27 20:48:00 2001] (plastoquinona, plastocianina)[Author ID1: at Mon Aug 27 20:48:00 2001]

    [Author ID0: at ]

    [Author ID1: at Sun Sep 2 17:07:00 2001]

    -->Tilacoides granales[Author ID1: at Mon Aug 27 20:48:00 2001][Author ID1: at Mon Aug 27 20:53:00 2001]

    Tienen una [Author ID1: at Mon Aug 27 20:48:00 2001]relación[Author ID1: at Mon Aug 27 20:52:00 2001] clorofila a/b menor q la de los [Author ID1: at Mon Aug 27 20:48:00 2001]tilacoides[Author ID1: at Mon Aug 27 20:49:00 2001] [Author ID1: at Mon Aug 27 20:48:00 2001]estromales 4/3 por 4/1. desde el punto de vista funciona[Author ID1: at Mon Aug 27 20:49:00 2001]l[Author ID1: at Sun Sep 2 17:12:00 2001] [Author ID1: at Mon Aug 27 20:49:00 2001]los granales tienen PS II aunque en los márgenes pueden tener PS I[Author ID1: at Sun Sep 2 18:35:00 2001].[Author ID1: at Sun Sep 2 18:36:00 2001] [Author ID1: at Sun Sep 2 18:35:00 2001][Author ID1: at Mon Aug 27 20:50:00 2001]

    -->Tilacoides[Author ID1: at Mon Aug 27 20:51:00 2001][Author ID1: at Mon Aug 27 20:53:00 2001]--> [Author ID1: at Mon Aug 27 20:50:00 2001][Author ID1: at Mon Aug 27 20:53:00 2001]-->estromales[Author ID1: at Mon Aug 27 20:51:00 2001][Author ID1: at Mon Aug 27 20:53:00 2001]

    Fosforilación y fotofosforilación cíclica.[Author ID1: at Mon Aug 27 20:51:00 2001] Los estromales tienen [Author ID1: at Sun Sep 2 18:35:00 2001]exclusivamente [Author ID1: at Sun Sep 2 18:37:00 2001]PS I, no tienen PS II[Author ID1: at Sun Sep 2 18:35:00 2001].[Author ID1: at Sun Sep 2 18:36:00 2001][Author ID0: at ]

    [Author ID1: at Mon Aug 27 20:53:00 2001]

    (Hoja 20) [Author ID1: at Mon Aug 27 20:53:00 2001]En los tilacoides se localizan los pigmentos fotosintéticos q captan la radiación, también se encuentran los componentes de la CTE, ligados a los [Author ID1: at Mon Aug 27 20:54:00 2001]tilacoides[Author ID1: at Mon Aug 27 20:55:00 2001] [Author ID1: at Mon Aug 27 20:54:00 2001]también esta la ATPasa q utiliza el potencial electroquímico generado [Author ID1: at Mon Aug 27 20:55:00 2001]para[Author ID1: at Fri Aug 31 02:33:00 2001] acoplar la [Author ID1: at Mon Aug 27 20:55:00 2001]síntesis[Author ID1: at Mon Aug 27 20:56:00 2001] [Author ID1: at Mon Aug 27 20:55:00 2001]de ATP.[Author ID1: at Mon Aug 27 20:56:00 2001]

    (Hoja 21[Author ID1: at Mon Aug 27 20:56:00 2001]-->)[Author ID1: at Mon Aug 27 20:56:00 2001][Author ID1: at Mon Aug 27 20:57:00 2001]--> Los pigmentos [Author ID1: at Mon Aug 27 20:56:00 2001][Author ID1: at Mon Aug 27 20:57:00 2001]-->están[Author ID1: at Mon Aug 27 21:05:00 2001][Author ID1: at Mon Aug 27 20:57:00 2001]--> asociados como [Author ID1: at Mon Aug 27 20:56:00 2001][Author ID1: at Mon Aug 27 20:57:00 2001]-->proteínas[Author ID1: at Mon Aug 27 21:05:00 2001][Author ID1: at Mon Aug 27 20:57:00 2001]--> formando 4 complejos:[Author ID1: at Mon Aug 27 20:56:00 2001][Author ID1: at Mon Aug 27 20:57:00 2001][Author ID1: at Mon Aug 27 20:57:00 2001]

    -->La m[Author ID1: at Mon Aug 27 21:04:00 2001][Author ID1: at Mon Aug 27 21:05:00 2001]-->ayor parte de la clorofila b se encuentra en el complejo antena del PS II[Author ID1: at Mon Aug 27 21:04:00 2001][Author ID1: at Mon Aug 27 21:05:00 2001].[Author ID1: at Mon Aug 27 21:06:00 2001][Author ID1: at Mon Aug 27 21:07:00 2001]

    -->(Hoja 22)[Author ID1: at Mon Aug 27 21:07:00 2001][Author ID1: at Mon Aug 27 21:07:00 2001] Existe una distribución espacial [Author ID1: at Mon Aug 27 21:07:00 2001]asimétrica[Author ID1: at Mon Aug 27 21:08:00 2001] [Author ID1: at Mon Aug 27 21:07:00 2001]de los PS I y PS II y sus componentes [Author ID1: at Mon Aug 27 21:08:00 2001]entre[Author ID1: at Mon Aug 27 21:11:00 2001] los tilacoides estromales y granales.[Author ID0: at ]

    El PS II se localiza en los [Author ID1: at Mon Aug 27 21:08:00 2001]tilacoides[Author ID1: at Mon Aug 27 21:09:00 2001] [Author ID1: at Mon Aug 27 21:08:00 2001]granales mientras q el PS I se [Author ID1: at Mon Aug 27 21:09:00 2001]localiza[Author ID1: at Mon Aug 27 21:11:00 2001] básicamente en los tilac[Author ID1: at Mon Aug 27 21:09:00 2001]o[Author ID1: at Mon Aug 27 21:11:00 2001]ides estromales y en las [Author ID1: at Mon Aug 27 21:09:00 2001]zonas[Author ID1: at Mon Aug 27 21:11:00 2001] marginales de [Author ID1: at Mon Aug 27 21:09:00 2001]tilacoides granales.[Author ID0: at ]

    Otros compuestos como el citocromo b[Author ID1: at Mon Aug 27 21:16:00 2001]6f[Author ID1: at Mon Aug 27 21:16:00 2001] esta repartido m[Author ID1: at Mon Aug 27 21:16:00 2001]á[Author ID1: at Sun Sep 2 17:27:00 2001]s [Author ID1: at Mon Aug 27 21:16:00 2001]uniformemente[Author ID1: at Mon Aug 27 21:17:00 2001].[Author ID1: at Mon Aug 27 21:16:00 2001][Author ID0: at ]

    El factor de acoplamiento [Author ID1: at Mon Aug 27 21:17:00 2001]para[Author ID1: at Fri Aug 31 02:33:00 2001] la síntesis de ATP se localiza básicamente en zona de los [Author ID1: at Mon Aug 27 21:17:00 2001]tilacoides[Author ID1: at Tue Aug 28 19:48:00 2001] [Author ID1: at Mon Aug 27 21:17:00 2001]estromales[Author ID1: at Mon Aug 27 21:18:00 2001].[Author ID1: at Mon Aug 27 21:17:00 2001][Author ID0: at ]

    Esta distribución implica q algunos intermediarios sean [Author ID1: at Mon Aug 27 21:18:00 2001]móviles[Author ID1: at Mon Aug 27 21:26:00 2001].[Author ID0: at ]

    Desde el punto de vista [Author ID1: at Mon Aug 27 21:18:00 2001]energético[Author ID1: at Mon Aug 27 21:26:00 2001] los sistemas antenales de deben mover de la zona granal a la estromal para la [Author ID1: at Mon Aug 27 21:18:00 2001]distribución[Author ID1: at Mon Aug 27 21:19:00 2001] [Author ID1: at Mon Aug 27 21:18:00 2001]de la [Author ID1: at Mon Aug 27 21:19:00 2001]energía[Author ID1: at Mon Aug 27 21:25:00 2001].[Author ID1: at Mon Aug 27 21:19:00 2001]

    (Hoja 23 [Author ID1: at Mon Aug 27 21:19:00 2001]Fig.[Author ID1: at Mon Aug 27 21:25:00 2001] 3.1)[Author ID1: at Mon Aug 27 21:19:00 2001] Los sistemas antena son marcadamente distintos den contra de [Author ID1: at Mon Aug 27 21:19:00 2001]los centros de [Author ID1: at Mon Aug 27 21:20:00 2001]reacción[Author ID1: at Mon Aug 27 21:25:00 2001]. La variación se debe a mecanismos adaptativos donde se han desarrollado los diferentes organismos [Author ID1: at Mon Aug 27 21:20:00 2001]fotosintéticos[Author ID1: at Mon Aug 27 21:21:00 2001].[Author ID1: at Mon Aug 27 21:20:00 2001][Author ID1: at Mon Aug 27 21:28:00 2001]

    Plantas superiores[Author ID1: at Mon Aug 27 21:28:00 2001]

    Clorofila a, b, etc. Hasta llegar la [Author ID1: at Mon Aug 27 21:28:00 2001]energía[Author ID1: at Mon Aug 27 21:39:00 2001] al PS II y PS I.[Author ID1: at Mon Aug 27 21:28:00 2001]

    Son procesos [Author ID1: at Mon Aug 27 21:29:00 2001]fotofísicos[Author ID1: at Mon Aug 27 21:39:00 2001] q transcurren en tiempos de piconanosegundos.[Author ID0: at ]

    La transferencia de [Author ID1: at Mon Aug 27 21:29:00 2001]energía[Author ID1: at Mon Aug 27 21:39:00 2001] no es directa. [Author ID1: at Mon Aug 27 21:29:00 2001]Se transmite la [Author ID1: at Mon Aug 27 21:30:00 2001]energía[Author ID1: at Mon Aug 27 21:39:00 2001] vibracional de [Author ID1: at Mon Aug 27 21:30:00 2001]una[Author ID1: at Tue Aug 28 19:49:00 2001] molécula a otra. Cuando las moléculas [Author ID1: at Mon Aug 27 21:30:00 2001]están[Author ID1: at Mon Aug 27 21:39:00 2001] muy cerca, las [Author ID1: at Mon Aug 27 21:30:00 2001]energías[Author ID1: at Mon Aug 27 21:39:00 2001] de [Author ID1: at Mon Aug 27 21:30:00 2001]excitación[Author ID1: at Mon Aug 27 21:31:00 2001] [Author ID1: at Mon Aug 27 21:30:00 2001]son capaces de pasar de un a otra (transferencia por resonancia [Author ID1: at Mon Aug 27 21:31:00 2001]de la transmisión)[Author ID1: at Mon Aug 27 21:42:00 2001]

    (Hoja 24 fig2)[Author ID1: at Mon Aug 27 21:43:00 2001]mecanismo tipo Foster[Author ID1: at Mon Aug 27 21:43:00 2001]

    La[Author ID1: at Tue Aug 28 19:49:00 2001] [Author ID1: at Mon Aug 27 21:43:00 2001]transferencia[Author ID1: at Mon Aug 27 21:48:00 2001] de [Author ID1: at Mon Aug 27 21:43:00 2001]energía[Author ID1: at Mon Aug 27 21:48:00 2001] vibracional [Author ID1: at Mon Aug 27 21:43:00 2001]también[Author ID1: at Mon Aug 27 21:48:00 2001] se da por mecanismo del excit[Author ID1: at Mon Aug 27 21:43:00 2001]ó[Author ID1: at Mon Aug 27 21:48:00 2001]n q se establece entre capas de [Author ID1: at Mon Aug 27 21:43:00 2001]moléculas[Author ID1: at Mon Aug 27 21:44:00 2001] [Author ID1: at Mon Aug 27 21:43:00 2001]similares.[Author ID0: at ]

    El 95-98 % de la [Author ID1: at Mon Aug 27 21:44:00 2001]energía[Author ID1: at Mon Aug 27 21:48:00 2001] se puede transferir de este modo para canalizar la [Author ID1: at Mon Aug 27 21:44:00 2001]energía[Author ID1: at Mon Aug 27 21:48:00 2001] a los centros de [Author ID1: at Mon Aug 27 21:44:00 2001]reacción[Author ID1: at Mon Aug 27 21:48:00 2001].[Author ID1: at Mon Aug 27 21:44:00 2001]

    La [Author ID1: at Mon Aug 27 21:45:00 2001]diferencia entre los dos tipos es la[Author ID1: at Mon Aug 27 21:46:00 2001] [Author ID1: at Mon Aug 27 21:48:00 2001]direccionalidad de la [Author ID1: at Mon Aug 27 21:46:00 2001]energía[Author ID1: at Mon Aug 27 21:48:00 2001]. En el mecanismo de [Author ID1: at Mon Aug 27 21:46:00 2001]Foster[Author ID1: at Mon Aug 27 21:46:00 2001] la [Author ID1: at Mon Aug 27 21:46:00 2001]energía[Author ID1: at Mon Aug 27 21:48:00 2001] va pasando de una molécula a otra q tienen espectros de [Author ID1: at Mon Aug 27 21:46:00 2001]absorción[Author ID1: at Mon Aug 27 21:47:00 2001] [Author ID1: at Mon Aug 27 21:46:00 2001]ligeramente diferentes.[Author ID1: at Mon Aug 27 21:47:00 2001]

    En [Author ID1: at Mon Aug 27 21:47:00 2001]el[Author ID1: at Tue Aug 28 11:38:00 2001] mecanismo de [Author ID1: at Mon Aug 27 21:47:00 2001]excitón[Author ID1: at Mon Aug 27 21:48:00 2001] la [Author ID1: at Mon Aug 27 21:47:00 2001]energía[Author ID1: at Mon Aug 27 21:49:00 2001] se deslocaliza en las moléculas adyacentes.[Author ID1: at Mon Aug 27 21:47:00 2001][Author ID0: at ]

    [Author ID1: at Tue Aug 28 11:39:00 2001]

    Papel de los carotenoides[Author ID1: at Tue Aug 28 11:39:00 2001]

    Dos básicamente:[Author ID1: at Tue Aug 28 11:40:00 2001][Author ID0: at ]

    Todos los organismos fotosintéticos poseen carotenoides [Author ID1: at Tue Aug 28 11:42:00 2001]excepto[Author ID1: at Tue Aug 28 11:43:00 2001] [Author ID1: at Tue Aug 28 11:42:00 2001]los mutantes en su maquinaria enzimática. Los diferentes carotenoides desde el punto de vista químico son tetraterpenos [Author ID1: at Tue Aug 28 11:43:00 2001](vía ac. mevalonico) [Author ID1: at Wed Sep 12 19:45:00 2001]con muchos dobles enlaces conjugados q les p[Author ID1: at Tue Aug 28 11:43:00 2001]ermiten captar la radiación del color naranja con un máximo de [Author ID1: at Tue Aug 28 11:44:00 2001]absorción de 450-490 nm.[Author ID1: at Tue Aug 28 11:45:00 2001]

    Están[Author ID1: at Tue Aug 28 11:49:00 2001] en el sistema antena y en el centro de [Author ID1: at Tue Aug 28 11:46:00 2001]reacción[Author ID1: at Tue Aug 28 11:49:00 2001] y forman parte de las membranas cloropl[Author ID1: at Tue Aug 28 11:46:00 2001]á[Author ID1: at Tue Aug 28 11:49:00 2001]sticas.[Author ID1: at Tue Aug 28 11:46:00 2001]

    La eficiencia de la transferencia es de 30-40 % [Author ID1: at Tue Aug 28 11:47:00 2001]frente[Author ID1: at Tue Aug 28 11:49:00 2001] al 90-95-99 % de las clorofilas.[Author ID1: at Tue Aug 28 11:47:00 2001][Author ID0: at ]

    También juegan un papel como [Author ID1: at Tue Aug 28 11:49:00 2001]agentes[Author ID1: at Tue Aug 28 11:55:00 2001] fotoprotectores ya q las me[Author ID1: at Tue Aug 28 11:49:00 2001]mbranas tilacoidales son fácilmente dañadas por la [Author ID1: at Tue Aug 28 11:50:00 2001]energía[Author ID1: at Tue Aug 28 11:55:00 2001] si es acumulada en gran cantidad y no puede ser disipada [Author ID1: at Tue Aug 28 11:50:00 2001]rápidamente[Author ID1: at Tue Aug 28 11:55:00 2001] por cal[Author ID1: at Tue Aug 28 11:50:00 2001]or o fluorescencia.[Author ID0: at ]

    Cuando las clorofilas [Author ID1: at Tue Aug 28 11:51:00 2001]están[Author ID1: at Tue Aug 28 11:55:00 2001] en triplete [Author ID1: at Tue Aug 28 11:51:00 2001]pueden[Author ID1: at Tue Aug 28 11:52:00 2001] [Author ID1: at Tue Aug 28 11:53:00 2001]reaccionar[Author ID1: at Tue Aug 28 11:55:00 2001] con O[Author ID1: at Tue Aug 28 11:53:00 2001]2[Author ID1: at Tue Aug 28 11:53:00 2001] dando radicales super[Author ID1: at Tue Aug 28 11:53:00 2001]ó[Author ID1: at Tue Aug 28 11:55:00 2001]xido [Author ID1: at Tue Aug 28 11:53:00 2001]actuando[Author ID1: at Tue Aug 28 11:55:00 2001] sobre las membranas mediante la [Author ID1: at Tue Aug 28 11:53:00 2001]Fotorrespiración[Author ID1: at Tue Sep 4 16:46:00 2001] llegando a [Author ID1: at Tue Aug 28 11:54:00 2001]degradarlas[Author ID1: at Tue Aug 28 11:55:00 2001].[Author ID1: at Tue Aug 28 11:54:00 2001]

    (Hoja 25 [Author ID1: at Tue Aug 28 11:56:00 2001]Fig.[Author ID1: at Tue Aug 28 12:20:00 2001] 3.7[Author ID1: at Tue Aug 28 11:56:00 2001] [Author ID1: at Tue Aug 28 11:57:00 2001]a)[Author ID1: at Tue Aug 28 11:57:00 2001] Puede ceder la [Author ID1: at Tue Aug 28 11:57:00 2001]energía[Author ID1: at Tue Aug 28 12:20:00 2001] [Author ID1: at Tue Aug 28 11:57:00 2001]transfiriéndola[Author ID1: at Tue Aug 28 11:58:00 2001] [Author ID1: at Tue Aug 28 11:57:00 2001]al carotenoide volviendo la clorofila al estado basal siendo capaz de volver a captar [Author ID1: at Tue Aug 28 11:58:00 2001]energía[Author ID1: at Tue Aug 28 12:20:00 2001]. El [Author ID1: at Tue Aug 28 11:58:00 2001]carotenoide[Author ID1: at Tue Aug 28 12:20:00 2001] vuelve al estado basal perdiendo la [Author ID1: at Tue Aug 28 11:58:00 2001]energía[Author ID1: at Tue Aug 28 12:20:00 2001] po[Author ID1: at Tue Aug 28 11:58:00 2001]r[Author ID1: at Tue Aug 28 12:25:00 2001] calor. [Author ID1: at Tue Aug 28 11:58:00 2001](b)[Author ID1: at Tue Aug 28 11:59:00 2001] el carotenoide en estado excitado no reacciona con el O[Author ID1: at Tue Aug 28 12:00:00 2001]2[Author ID1: at Tue Aug 28 12:00:00 2001] en forma de triplete mediante una epoxidaci[Author ID1: at Tue Aug 28 12:01:00 2001]ó[Author ID1: at Tue Aug 28 12:20:00 2001]n [Author ID1: at Tue Aug 28 12:01:00 2001]transformándose[Author ID1: at Tue Aug 28 12:02:00 2001] [Author ID1: at Tue Aug 28 12:01:00 2001]en epoxicarotenoide. Este puede volver el estado basal mediante una [Author ID1: at Tue Aug 28 12:02:00 2001]reacción[Author ID1: at Tue Aug 28 12:27:00 2001] de desepoxidaci[Author ID1: at Tue Aug 28 12:02:00 2001]ó[Author ID1: at Tue Aug 28 12:26:00 2001]n. [Author ID1: at Tue Aug 28 12:02:00 2001](d)[Author ID1: at Tue Aug 28 12:03:00 2001] esta [Author ID1: at Tue Aug 28 12:03:00 2001]reacción[Author ID1: at Tue Aug 28 12:26:00 2001] se puede dar con la [Author ID1: at Tue Aug 28 12:03:00 2001]actuación[Author ID1: at Tue Aug 28 12:04:00 2001] [Author ID1: at Tue Aug 28 12:03:00 2001]de las xantofilas.[Author ID0: at ]

    Las reacciones de [Author ID1: at Tue Aug 28 12:04:00 2001]epoxidación[Author ID1: at Tue Aug 28 12:26:00 2001] se dan en la cara estromal a pH de 7.5-8. [Author ID1: at Tue Aug 28 12:04:00 2001]la [Author ID1: at Tue Aug 28 12:05:00 2001]reacción[Author ID1: at Tue Aug 28 12:27:00 2001] se revierte en la zona luminal a un pH de 5.[Author ID0: at ]

    [Author ID1: at Tue Aug 28 12:05:00 2001]

    [Author ID0: at ]

    [Author ID1: at Tue Aug 28 12:29:00 2001]

    Biogénesis de [Author ID1: at Tue Aug 28 12:05:00 2001]cloroplastos[Author ID1: at Tue Aug 28 12:06:00 2001][Author ID1: at Tue Aug 28 12:27:00 2001]

    [Author ID1: at Tue Aug 28 12:06:00 2001]

    En el curso de la [Author ID1: at Tue Aug 28 12:07:00 2001]diferenciación[Author ID1: at Tue Aug 28 12:30:00 2001] de los [Author ID1: at Tue Aug 28 12:07:00 2001]tejidos[Author ID1: at Tue Aug 28 12:30:00 2001] [Author ID1: at Tue Aug 28 12:07:00 2001]fotosintéticos[Author ID1: at Tue Aug 28 12:30:00 2001] a partir de las células meristem[Author ID1: at Tue Aug 28 12:07:00 2001]á[Author ID1: at Tue Aug 28 12:30:00 2001]ticas se va a formar la maquinaria [Author ID1: at Tue Aug 28 12:07:00 2001]enzimática[Author ID1: at Tue Aug 28 12:08:00 2001].[Author ID1: at Tue Aug 28 12:07:00 2001][Author ID0: at ]

    En las células meristem[Author ID1: at Tue Aug 28 12:08:00 2001]á[Author ID1: at Tue Aug 28 12:30:00 2001]ticas existen [Author ID1: at Tue Aug 28 12:08:00 2001]orgánulos[Author ID1: at Tue Aug 28 12:30:00 2001] muy [Author ID1: at Tue Aug 28 12:08:00 2001]pequeños[Author ID1: at Tue Aug 28 12:30:00 2001] q poseen doble membrana con la [Author ID1: at Tue Aug 28 12:08:00 2001]dotación[Author ID1: at Tue Aug 28 12:09:00 2001] [Author ID1: at Tue Aug 28 12:08:00 2001]genética[Author ID1: at Tue Aug 28 12:30:00 2001] parecida a la q tienen los cloroplastos desarrollados.[Author ID0: at ]

    A partir de estos [Author ID1: at Tue Aug 28 12:09:00 2001]orgánulos[Author ID1: at Tue Aug 28 12:30:00 2001] de da el desarrollo por dos [Author ID1: at Tue Aug 28 12:09:00 2001]vías[Author ID1: at Tue Aug 28 12:30:00 2001]: [Author ID1: at Tue Aug 28 12:09:00 2001](Hoja 26)[Author ID1: at Tue Aug 28 12:10:00 2001]

  • Con[Author ID1: at Tue Aug 28 19:49:00 2001] luz:[Author ID1: at Tue Aug 28 12:11:00 2001] se da la [Author ID1: at Tue Aug 28 12:11:00 2001]invaginación[Author ID1: at Tue Aug 28 12:30:00 2001] de la membrana interna q va creciendo hacia el interior, se va situando en una [Author ID1: at Tue Aug 28 12:11:00 2001]disposición[Author ID1: at Tue Aug 28 12:12:00 2001] [Author ID1: at Tue Aug 28 12:11:00 2001]longitudinal según al eje mayor, se da el aplastamiento y se independiza de la membrana [Author ID1: at Tue Aug 28 12:12:00 2001]externa[Author ID1: at Tue Aug 28 12:31:00 2001] [Author ID1: at Tue Aug 28 12:12:00 2001]formándose[Author ID1: at Tue Aug 28 12:13:00 2001] [Author ID1: at Tue Aug 28 12:12:00 2001]los tilacoides. Paralelamente se sintetizan masivamente [Author ID1: at Tue Aug 28 12:13:00 2001]proteínas[Author ID1: at Tue Aug 28 12:30:00 2001], clorofilas, pigmentos q van a transformar la [Author ID1: at Tue Aug 28 12:13:00 2001]energía[Author ID1: at Tue Aug 28 12:30:00 2001] [Author ID1: at Tue Aug 28 12:13:00 2001]luminosa[Author ID1: at Tue Aug 28 12:31:00 2001] en [Author ID1: at Tue Aug 28 12:13:00 2001]electroquímica[Author ID1: at Tue Aug 28 12:14:00 2001].[Author ID1: at Tue Aug 28 12:13:00 2001]-->[Author ID1: at Tue Aug 28 12:14:00 2001][Author ID1: at Tue Aug 28 12:10:00 2001]

  • En[Author ID1: at Tue Aug 28 19:49:00 2001] oscuridad:[Author ID1: at Tue Aug 28 12:14:00 2001] las invaginaciones dan lugar a estructuras tubulares q van a dar[Author ID1: at Tue Aug 28 12:14:00 2001],[Author ID1: at Tue Aug 28 12:15:00 2001] por [Author ID1: at Tue Aug 28 12:14:00 2001]combinación[Author ID1: at Tue Aug 28 12:15:00 2001] [Author ID1: at Tue Aug 28 12:14:00 2001]de 3 tubos, redes [Author ID1: at Tue Aug 28 12:15:00 2001]cúbicas[Author ID1: at Tue Aug 28 12:31:00 2001] de 300 [Author ID1: at Tue Aug 28 12:15:00 2001]Å de diámetro constituyendo los cuerpos prolamelares. [Author ID1: at Tue Aug 28 12:17:00 2001]Si estos cuerpos se someten a luz se da la transformación a los verdaderos tilacoides. A [Author ID1: at Tue Aug 28 12:18:00 2001]continuación[Author ID1: at Tue Aug 28 12:19:00 2001] [Author ID1: at Tue Aug 28 12:18:00 2001]se da el desarrollo de las actividades [Author ID1: at Tue Aug 28 12:19:00 2001]fotosintéticas[Author ID1: at Tue Aug 28 12:31:00 2001].[Author ID1: at Tue Aug 28 12:19:00 2001]-->[Author ID1: at Tue Aug 28 12:31:00 2001][Author ID1: at Tue Aug 28 12:10:00 2001]

  • [Author ID1: at Tue Aug 28 12:33:00 2001]

    Una[Author ID1: at Tue Aug 28 13:01:00 2001] vez sintetizados los pigmentos, cloroplastos y [Author ID1: at Tue Aug 28 12:33:00 2001]proteínas[Author ID1: at Tue Aug 28 13:01:00 2001] se [Author ID1: at Tue Aug 28 12:33:00 2001]ven[Author ID1: at Tue Aug 28 19:50:00 2001] la [Author ID1: at Tue Aug 28 12:33:00 2001]aparición[Author ID1: at Tue Aug 28 13:01:00 2001] secuencial de las [Author ID1: at Tue Aug 28 12:33:00 2001]actividades[Author ID1: at Tue Aug 28 12:34:00 2001] [Author ID1: at Tue Aug 28 12:33:00 2001]fotosintéticas. Aparece antes la actividad ligada al fotosistema I (PS I) q la del PS II. [Author ID1: at Tue Aug 28 12:34:00 2001]Nada mas iluminar las hojas se ve actividad del PS I.[Author ID0: at ]

    La del PS II se da m[Author ID1: at Tue Aug 28 12:35:00 2001]á[Author ID1: at Tue Aug 28 13:02:00 2001]s [Author ID1: at Tue Aug 28 12:35:00 2001]paulatinamente, a las 2 horas los niveles de[Author ID1: at Tue Aug 28 12:36:00 2001] desprendimiento de O[Author ID1: at Tue Aug 28 12:37:00 2001]2[Author ID1: at Tue Aug 28 12:37:00 2001] son equiparables a los niveles de actividad fotosintética.[Author ID1: at Tue Aug 28 12:37:00 2001] A las 2 horas las tasas de desprendimiento de O[Author ID1: at Tue Aug 28 13:03:00 2001]2[Author ID1: at Tue Aug 28 13:04:00 2001] son 80 veces superiores q cuando se han desarro[Author ID1: at Tue Aug 28 13:04:00 2001]l[Author ID1: at Tue Aug 28 13:07:00 2001]lado [Author ID1: at Tue Aug 28 13:04:00 2001]totalmente[Author ID1: at Tue Aug 28 13:05:00 2001] [Author ID1: at Tue Aug 28 13:04:00 2001]los [Author ID1: at Tue Aug 28 13:05:00 2001]cloroplastos[Author ID1: at Tue Aug 28 13:07:00 2001]. Esto se debe a q la actividad fotosintética de los PS es [Author ID1: at Tue Aug 28 13:05:00 2001]más[Author ID1: at Tue Aug 28 19:50:00 2001] [Author ID1: at Tue Aug 28 13:05:00 2001]eficiente;[Author ID1: at Tue Aug 28 19:50:00 2001] en cambio la [Author ID1: at Tue Aug 28 13:05:00 2001]actividad[Author ID1: at Tue Aug 28 13:06:00 2001] [Author ID1: at Tue Aug 28 13:05:00 2001]de los sistemas antena no es tan alta q cuando ya [Author ID1: at Tue Aug 28 13:06:00 2001]están[Author ID1: at Tue Aug 28 13:07:00 2001] totalmente desarrollados. Se necesita mayor [Author ID1: at Tue Aug 28 13:06:00 2001]energía[Author ID1: at Tue Aug 28 13:07:00 2001] ya q no [Author ID1: at Tue Aug 28 13:06:00 2001]están[Author ID1: at Tue Aug 28 13:07:00 2001] tan d[Author ID1: at Tue Aug 28 13:06:00 2001]esarrollados.[Author ID0: at ]

    Las tasas de fijación de CO[Author ID1: at Tue Aug 28 13:07:00 2001]2[Author ID1: at Tue Aug 28 13:07:00 2001] [Author ID1: at Tue Aug 28 13:02:00 2001]se observan transcurridas 3 horas tras la iluminación. El [Author ID1: at Tue Aug 28 13:08:00 2001]-->punto de compensación[Author ID1: at Tue Aug 28 13:08:00 2001][Author ID1: at Thu Aug 30 18:42:00 2001]--> [Author ID1: at Tue Aug 28 13:08:00 2001][Author ID1: at Thu Aug 30 18:42:00 2001]de CO[Author ID1: at Tue Aug 28 13:08:00 2001]2[Author ID1: at Tue Aug 28 13:08:00 2001] no se alcanza hasta m[Author ID1: at Tue Aug 28 13:09:00 2001]á[Author ID1: at Mon Sep 3 11:55:00 2001]s de 30 horas.[Author ID0: at ]

    El [Author ID1: at Tue Aug 28 13:09:00 2001]-->punto de [Author ID1: at Tue Aug 28 13:09:00 2001][Author ID1: at Thu Aug 30 18:42:00 2001]-->compensación[Author ID1: at Tue Aug 28 13:10:00 2001][Author ID1: at Thu Aug 30 18:42:00 2001] [Author ID1: at Tue Aug 28 13:09:00 2001]son las tasas de fijación de CO[Author ID1: at Tue Aug 28 13:10:00 2001]2[Author ID1: at Tue Aug 28 13:10:00 2001] q contrarrestan las tasas de [Author ID1: at Tue Aug 28 13:10:00 2001]respiración[Author ID1: at Tue Aug 28 13:11:00 2001] [Author ID1: at Tue Aug 28 13:10:00 2001]mitocondrial o [Author ID1: at Tue Aug 28 13:11:00 2001]Fotorrespiración[Author ID1: at Tue Sep 4 16:46:00 2001].[Author ID0: at ]

    Los procesos del ciclo de [Author ID1: at Tue Aug 28 13:11:00 2001]Calvin[Author ID1: at Tue Aug 28 13:12:00 2001] [Author ID1: at Tue Aug 28 12:57:00 2001]son [Author ID1: at Tue Aug 28 13:12:00 2001]más[Author ID1: at Tue Aug 28 19:50:00 2001] lentos, no son tan [Author ID1: at Tue Aug 28 13:12:00 2001]rápidos[Author ID1: at Tue Aug 28 13:21:00 2001] en las etapas de reverdecimiento.[Author ID1: at Tue Aug 28 13:12:00 2001][Author ID0: at ]

    La luz y las fitoquininas juegan un papel regulador en [Author ID1: at Tue Aug 28 13:13:00 2001]el[Author ID1: at Tue Aug 28 19:50:00 2001] proceso de formación de la maquinaria enzimática.[Author ID0: at ]

    La luz a [Author ID1: at Tue Aug 28 13:13:00 2001]través[Author ID1: at Tue Aug 28 13:21:00 2001] del [Author ID1: at Tue Aug 28 13:13:00 2001]citocromo[Author ID1: at Tue Aug 28 13:14:00 2001] [Author ID1: at Tue Aug 28 13:13:00 2001]controla los procesos de protoclorofilida a clorofilida.[Author ID0: at ]

    Las fitoquininas controlan el proceso porque favorecen los [Author ID1: at Tue Aug 28 13:14:00 2001]apilamientos[Author ID1: at Tue Aug 28 13:21:00 2001] granales y [Author ID1: at Tue Aug 28 13:14:00 2001]síntesis[Author ID1: at Tue Aug 28 13:15:00 2001] [Author ID1: at Tue Aug 28 13:14:00 2001]de [Author ID1: at Tue Aug 28 13:15:00 2001]proteínas[Author ID1: at Tue Aug 28 13:21:00 2001] q forman los complejos clorofila-[Author ID1: at Tue Aug 28 13:15:00 2001]proteína[Author ID1: at Tue Aug 28 13:21:00 2001] de los sistemas antena.[Author ID1: at Tue Aug 28 13:15:00 2001][Author ID0: at ]

    Los cloroplastos de dividen por estrangulamiento de la membrana.[Author ID1: at Tue Aug 28 13:16:00 2001] Son una clase de plastidios q contienen una cubierta de doble membrana como los leucoplastos o [Author ID1: at Tue Aug 28 13:17:00 2001]cromoplastos[Author ID1: at Tue Aug 28 13:18:00 2001].[Author ID1: at Tue Aug 28 13:17:00 2001][Author ID0: at ]

    Aquellos plastos con pigmentos q no sean clorofila son los cromoplastos.[Author ID0: at ]

    Entre los leucoplastos [Author ID1: at Tue Aug 28 13:18:00 2001]están[Author ID1: at Tue Aug 28 13:21:00 2001] los [Author ID1: at Tue Aug 28 13:18:00 2001]amiloplastos[Author ID1: at Tue Aug 28 13:19:00 2001] [Author ID1: at Tue Aug 28 13:18:00 2001]q almacenan [Author ID1: at Tue Aug 28 13:19:00 2001]almidón[Author ID1: at Tue Aug 28 13:22:00 2001] y los proteinoplastos q almacenan [Author ID1: at Tue Aug 28 13:19:00 2001]proteínas[Author ID1: at Tue Aug 28 13:22:00 2001]; también [Author ID1: at Tue Aug 28 13:19:00 2001]están[Author ID1: at Tue Aug 28 13:22:00 2001] los oleoplastos q almacenan aceite, [Author ID1: at Tue Aug 28 13:19:00 2001]lípido[Author ID1: at Tue Aug 28 13:22:00 2001]s.[Author ID0: at ]

    Los cloroplastos pueden transformarse en otros plastos sobre todo en [Author ID1: at Tue Aug 28 13:23:00 2001]cromoplastos cuando se degradan las clorofilas.[Author ID1: at Tue Aug 28 13:29:00 2001][Author ID0: at ]

    Los cloroplastos tienen [Author ID1: at Tue Aug 28 13:30:00 2001]anatomía[Author ID1: at Tue Aug 28 13:32:00 2001] [Author ID1: at Tue Aug 28 13:30:00 2001]genética[Author ID1: at Tue Aug 28 13:32:00 2001] parcial, tienen la maquinaria par[Author ID1: at Tue Aug 28 13:30:00 2001]a[Author ID1: at Tue Aug 28 13:32:00 2001] la [Author ID1: at Tue Aug 28 13:30:00 2001]replicación del DNA, [Author ID1: at Tue Aug 28 13:32:00 2001]trascripción[Author ID1: at Tue Aug 28 13:34:00 2001] del RNA y [Author ID1: at Tue Aug 28 13:32:00 2001]traducción[Author ID1: at Tue Aug 28 13:33:00 2001] [Author ID1: at Tue Aug 28 13:32:00 2001]de [Author ID1: at Tue Aug 28 13:33:00 2001]proteínas[Author ID1: at Tue Aug 28 13:34:00 2001].[Author ID0: at ]

    Se hereda de modo no mendeliano, [Author ID1: at Tue Aug 28 13:33:00 2001]vía[Author ID1: at Tue Aug 28 13:34:00 2001] materna.[Author ID1: at Tue Aug 28 13:33:00 2001] E[Author ID1: at Tue Aug 28 13:34:00 2001]l DNA es circular con doble [Author ID1: at Tue Aug 28 13:35:00 2001]hélice[Author ID1: at Tue Aug 28 13:41:00 2001]. El DNA esta localizado en los nucleoides, cada uno puede contener 4 cromosomas. [Author ID1: at Tue Aug 28 13:35:00 2001]Se puede separar mediante ultracentrifugaci[Author ID1: at Tue Aug 28 13:36:00 2001]ó[Author ID1: at Tue Aug 28 13:42:00 2001]n y por gradiante de ClCs.[Author ID1: at Tue Aug 28 13:36:00 2001]

    Los constituyentes del cloroplasto [Author ID1: at Tue Aug 28 13:37:00 2001]están[Author ID1: at Tue Aug 28 13:42:00 2001] sintetizados de modo coordinado por inducción del genoma nuclear y cloropl[Author ID1: at Tue Aug 28 13:37:00 2001]á[Author ID1: at Tue Aug 28 19:51:00 2001]stico. [Author ID1: at Tue Aug 28 13:37:00 2001]Dentro de los constituyentes del cloroplasto tenemos unas [Author ID1: at Tue Aug 28 13:38:00 2001]proteínas[Author ID1: at Tue Aug 28 13:42:00 2001] como son la subunidad grande de la [Author ID1: at Tue Aug 28 13:38:00 2001]RUBISCO[Author ID1: at Tue Aug 28 13:42:00 2001]. [Author ID1: at Tue Aug 28 13:38:00 2001]Este enzima tiene dos cadenas [Author ID1: at Tue Aug 28 13:39:00 2001]polipeptídicas[Author ID1: at Tue Aug 28 13:41:00 2001] una constituida por 8 subunidades codificadas por el genoma[Author ID1: at Tue Aug 28 13:39:00 2001] del[Author ID1: at Thu Aug 30 18:47:00 2001] [Author ID1: at Tue Aug 28 13:39:00 2001]cloroplasto [Author ID1: at Thu Aug 30 18:47:00 2001](la Subunidad grande[Author ID1: at Thu Aug 30 18:48:00 2001], donde [Author ID1: at Fri Aug 31 17:24:00 2001]están[Author ID1: at Fri Aug 31 17:25:00 2001] los centros [Author ID1: at Fri Aug 31 17:24:00 2001]catalíticos[Author ID1: at Fri Aug 31 17:25:00 2001] del enzima[Author ID1: at Fri Aug 31 17:24:00 2001])[Author ID1: at Thu Aug 30 18:48:00 2001],[Author ID1: at Tue Aug 28 13:39:00 2001] y otras 8 subunidades codificadas por el genoma [Author ID1: at Tue Aug 28 13:40:00 2001]nuclear (la Subunidad [Author ID1: at Thu Aug 30 18:48:00 2001]pequeña[Author ID1: at Thu Aug 30 18:49:00 2001])[Author ID1: at Thu Aug 30 18:48:00 2001].[Author ID1: at Tue Aug 28 13:40:00 2001] [Author ID0: at ]

    La RUBISCO [Author ID1: at Tue Aug 28 13:41:00 2001]constituye hasta un 50 % de la [Author ID1: at Tue Aug 28 13:43:00 2001]proteína[Author ID1: at Tue Aug 28 13:44:00 2001] soluble de la hoja.[Author ID1: at Tue Aug 28 13:43:00 2001][Author ID0: at ]

    Otros constituyentes codificados por su propio genoma son:[Author ID1: at Tue Aug 28 13:44:00 2001]

    Las [Author ID1: at Tue Aug 28 13:55:00 2001]proteínas[Author ID1: at Tue Aug 28 14:01:00 2001] del cloroplasto [Author ID1: at Tue Aug 28 13:55:00 2001]están[Author ID1: at Tue Aug 28 14:01:00 2001] sintetizadas en los ribosomas 70s inhibidos por [Author ID1: at Tue Aug 28 13:55:00 2001]cloranfenicol[Author ID1: at Tue Aug 28 14:01:00 2001]. [Author ID1: at Tue Aug 28 13:55:00 2001]Los citoplasmáticos son 80s inhibidos por la cicloheximida.[Author ID0: at ]

    Los [Author ID1: at Tue Aug 28 13:56:00 2001]constituyentes codificados por el genoma nuclear entran a [Author ID1: at Tue Aug 28 13:57:00 2001]través[Author ID1: at Tue Aug 28 14:01:00 2001] de la [Author ID1: at Tue Aug 28 13:57:00 2001]membrana.[Author ID0: at ]

    No se conoce la [Author ID1: at Tue Aug 28 13:57:00 2001]síntesis[Author ID1: at Tue Aug 28 13:58:00 2001] [Author ID1: at Tue Aug 28 13:57:00 2001]en cloroplastos y q salgan al citoplasma. La [Author ID1: at Tue Aug 28 13:58:00 2001]anatomía[Author ID1: at Tue Aug 28 14:01:00 2001] [Author ID1: at Tue Aug 28 13:58:00 2001]genética[Author ID1: at Tue Aug 28 14:01:00 2001] parcial es porque intervienen genes del cloroplasto y del [Author ID1: at Tue Aug 28 13:58:00 2001]núcleo[Author ID1: at Tue Aug 28 13:59:00 2001].[Author ID1: at Tue Aug 28 13:58:00 2001][Author ID0: at ]

    También se plantea q los cloroplastos derivan de la inclusión de un simbionte q [Author ID1: at Tue Aug 28 13:59:00 2001]posiblemente[Author ID1: at Tue Aug 28 14:00:00 2001] [Author ID1: at Tue Aug 28 13:59:00 2001]fuera un antecesor [Author ID1: at Tue Aug 28 14:00:00 2001]común[Author ID1: at Tue Aug 28 14:01:00 2001] a las algas verdeazuladas.[Author ID0: at ]

    [Author ID1: at Tue Aug 28 14:00:00 2001]

    Extracción de los [Author ID1: at Tue Aug 28 14:00:00 2001]cloroplastos[Author ID1: at Tue Aug 28 14:01:00 2001]

    Los cloroplastos se extraen en un medio tamponado en el q se incluyen distintos componentes, cuya finalidad es mantener los enlaces SH. [Author ID1: at Tue Aug 28 14:01:00 2001]También se incluye una sal de Mg para[Author ID1: at Tue Aug 28 14:02:00 2001] [Author ID1: at Tue Aug 28 14:03:00 2001]mantener [Author ID1: at Tue Aug 28 14:02:00 2001]tasas altas de desprendimiento de O[Author ID1: at Tue Aug 28 14:03:00 2001]2[Author ID1: at Tue Aug 28 14:04:00 2001], sales de Mn para la lisis del agua.[Author ID0: at ]

    Se [Author ID1: at Tue Aug 28 14:04:00 2001]añade[Author ID1: at Tue Aug 28 14:06:00 2001] una [Author ID1: at Tue Aug 28 14:04:00 2001]concentración[Author ID1: at Tue Aug 28 14:05:00 2001] [Author ID1: at Tue Aug 28 14:04:00 2001]0.2-0.4 M de sacarosa, glucosa o sorbito[Author ID1: at Tue Aug 28 14:05:00 2001]l[Author ID1: at Tue Aug 28 14:06:00 2001] para evitar q por choque [Author ID1: at Tue Aug 28 14:07:00 2001]osmótico[Author ID1: at Tue Aug 28 14:11:00 2001] se rompan los cloroplastos.[Author ID1: at Tue Aug 28 14:07:00 2001][Author ID0: at ]

    También se evita la [Author ID1: at Tue Aug 28 14:08:00 2001]acción[Author ID1: at Tue Aug 28 14:11:00 2001] de taninos [Author ID1: at Tue Aug 28 14:08:00 2001]añadiendo[Author ID1: at Tue Aug 28 14:11:00 2001] moléculas q los secuestren.[Author ID0: at ]

    Se homogeneiz[Author ID1: at Tue Aug 28 14:08:00 2001]a el tejido vegetal y se filtra por capas de muselina. Se centr[Author ID1: at Tue Aug 28 14:09:00 2001]i[Author ID1: at Tue Aug 28 19:52:00 2001]fuga, se dan lavados para corregir mayor [Author ID1: at Tue Aug 28 14:09:00 2001]purificación[Author ID1: at Tue Aug 28 14:10:00 2001].[Author ID1: at Tue Aug 28 14:09:00 2001][Author ID0: at ]

    También se puede centrifugar por gradiente de densidad. A continuación estos cloroplastos se pueden utilizar para los diferentes experimentos.[Author ID1: at Tue Aug 28 14:10:00 2001][Author ID0: at ]

    Si se hace la dilución en un medio orgánico perdemos los pigmentos[Author ID1: at Tue Aug 28 14:11:00 2001].[Author ID1: at Tue Aug 28 14:06:00 2001]

    Un 20 % de los cloroplastos son materia seca de la q un 60 % son [Author ID1: at Tue Aug 28 14:12:00 2001]proteínas[Author ID1: at Tue Aug 28 14:14:00 2001], un 15 % lípidos, 4 % clorofila, 0.7 % [Author ID1: at Tue Aug 28 14:12:00 2001]carotenoides[Author ID1: at Tue Aug 28 14:13:00 2001],[Author ID1: at Tue Aug 28 14:12:00 2001] 2 % RNA, un porcentaje [Author ID1: at Tue Aug 28 14:13:00 2001]más[Author ID1: at Tue Aug 28 19:52:00 2001] pequeño corresponde a DNA, aa libres, iones[Author ID1: at Tue Aug 28 14:13:00 2001] inorgánicos[Author ID1: at Tue Aug 28 14:14:00 2001], [Author ID1: at Tue Aug 28 14:13:00 2001]fenoles[Author ID1: at Tue Aug 28 14:14:00 2001],[Author ID1: at Tue Aug 28 14:13:00 2001] metabolitos secundarios...[Author ID1: at Tue Aug 28 14:14:00 2001]

    [Author ID0: at ]

    [Author ID1: at Tue Aug 28 14:15:00 2001]

    [Author ID1: at Thu Aug 30 20:52:00 2001]

    -->Tema 6 conversión energética[Author ID1: at Tue Aug 28 14:15:00 2001][Author ID1: at Fri Aug 31 14:43:00 2001]

    [Author ID1: at Tue Aug 28 14:15:00 2001]

    Implica intermediarios para conducir los e[Author ID1: at Tue Aug 28 14:16:00 2001]-[Author ID1: at Tue Aug 28 14:16:00 2001] de la [Author ID1: at Tue Aug 28 14:16:00 2001]fotosíntesis[Author ID1: at Tue Aug 28 14:17:00 2001] del agua hasta el NADPH[Author ID1: at Tue Aug 28 14:16:00 2001]. Tiene un proceso endoerg[Author ID1: at Tue Aug 28 14:17:00 2001]ó[Author ID1: at Tue Aug 28 14:18:00 2001]nico (requiere [Author ID1: at Tue Aug 28 14:17:00 2001]energía[Author ID1: at Tue Aug 28 14:18:00 2001]) y otro exoerg[Author ID1: at Tue Aug 28 14:17:00 2001]ó[Author ID1: at Tue Aug 28 14:18:00 2001]nico (libera [Author ID1: at Tue Aug 28 14:17:00 2001]energía[Author ID1: at Tue Aug 28 14:18:00 2001])[Author ID1: at Tue Aug 28 14:17:00 2001].[Author ID0: at ]

    La [Author ID1: at Tue Aug 28 14:18:00 2001]fotosíntesis[Author ID1: at Tue Aug 28 14:22:00 2001] es un proceso endoergónico. Se produce la [Author ID1: at Tue Aug 28 14:18:00 2001]síntesis[Author ID1: at Tue Aug 28 14:19:00 2001] [Author ID1: at Tue Aug 28 14:18:00 2001]de [Author ID1: at Tue Aug 28 14:19:00 2001]compuestos[Author ID1: at Tue Aug 28 14:22:00 2001] [Author ID1: at Tue Aug 28 14:19:00 2001]orgánicos[Author ID1: at Tue Aug 28 14:22:00 2001] a partir de agua. Como el CO[Author ID1: at Tue Aug 28 14:19:00 2001]2[Author ID1: at Tue Aug 28 14:20:00 2001] y el H[Author ID1: at Tue Aug 28 14:19:00 2001]2[Author ID1: at Tue Aug 28 14:20:00 2001]O tienen un nivel energético muy bajo respecto al CH[Author ID1: at Tue Aug 28 14:20:00 2001]2[Author ID1: at Tue Aug 28 14:20:00 2001]O, n va la [Author ID1: at Tue Aug 28 14:20:00 2001]reacción[Author ID1: at Tue Aug 28 14:22:00 2001] [Author ID1: at Tue Aug 28 14:20:00 2001]espontáneamente[Author ID1: at Tue Aug 28 14:21:00 2001] [Author ID1: at Tue Aug 28 14:20:00 2001]a la derecha, sino q necesita [Author ID1: at Tue Aug 28 14:21:00 2001]energía[Author ID1: at Tue Aug 28 14:22:00 2001] fot[Author ID1: at Tue Aug 28 14:21:00 2001]ó[Author ID1: at Tue Aug 28 14:22:00 2001]nica a partir de la membrana del cloroplasto y es transformada en [Author ID1: at Tue Aug 28 14:21:00 2001]energía[Author ID1: at Tue Aug 28 14:22:00 2001] [Author ID1: at Tue Aug 28 14:21:00 2001]química[Author ID1: at Tue Aug 28 14:22:00 2001].[Author ID1: at Tue Aug 28 14:21:00 2001][Author ID0: at ]

    La [Author ID1: at Tue Aug 28 14:28:00 2001]energía[Author ID1: at Tue Aug 28 14:29:00 2001] global es ligeramente superior a la [Author ID1: at Tue Aug 28 14:28:00 2001]energía[Author ID1: at Tue Aug 28 14:29:00 2001] de los productos [Author ID1: at Tue Aug 28 14:28:00 2001]así[Author ID1: at Tue Aug 28 14:29:00 2001] do se da la [Author ID1: at Tue Aug 28 14:28:00 2001]reacción[Author ID1: at Tue Aug 28 14:29:00 2001] [Author ID1: at Tue Aug 28 14:28:00 2001]inversa[Author ID1: at Tue Aug 28 14:29:00 2001] [Author ID1: at Tue Aug 28 14:28:00 2001]espontánea[Author ID1: at Tue Aug 28 14:29:00 2001]. [Author ID1: at Tue Aug 28 14:28:00 2001][Author ID0: at ]

    La conversión energética se lleva a cabo en la membrana de los [Author ID1: at Tue Aug 28 14:29:00 2001]tilacoides[Author ID1: at Tue Aug 28 14:30:00 2001] [Author ID1: at Tue Aug 28 14:29:00 2001]transformándola en NADH y[Author ID1: at Tue Aug 28 14:30:00 2001] [Author ID1: at Tue Aug 28 14:37:00 2001]ATP usada en la fase oscura del Ciclo de Calvin.[Author ID0: at ]

    En la fase luminosa el lumen se carga de H[Author ID1: at Tue Aug 28 14:30:00 2001]+[Author ID1: at Tue Aug 28 14:31:00 2001], crea un gradiente electroquímico [Author ID1: at Tue Aug 28 14:31:00 2001]usado[Author ID1: at Tue Aug 28 14:37:00 2001] para la [Author ID1: at Tue Aug 28 14:31:00 2001]síntesis[Author ID1: at Tue Aug 28 14:37:00 2001] de [Author ID1: at Tue Aug 28 14:31:00 2001]ATP[Author ID1: at Tue Aug 28 14:37:00 2001]. [Author ID1: at Tue Aug 28 14:31:00 2001]La transferencia de e[Author ID1: at Tue Aug 28 14:32:00 2001]-[Author ID1: at Tue Aug 28 14:32:00 2001] del agua al NADPH requiere el aporte de fotones. Por cada e[Author ID1: at Tue Aug 28 14:32:00 2001]-[Author ID1: at Tue Aug 28 14:33:00 2001] transferido del agua al NADPH se necesitan 2 fotones q van a ser captados por el PS II y PS I. Como para [Author ID1: at Tue Aug 28 14:33:00 2001]oxidar[Author ID1: at Tue Aug 28 14:37:00 2001] dos [Author ID1: at Tue Aug 28 14:33:00 2001]moléculas[Author ID1: at Tue Aug 28 14:34:00 2001] [Author ID1: at Tue Aug 28 14:33:00 2001]de [Author ID1: at Tue Aug 28 14:34:00 2001]H[Author ID1: at Tue Aug 28 14:35:00 2001]2[Author ID1: at Tue Aug 28 14:35:00 2001]O[Author ID1: at Tue Aug 28 14:35:00 2001] se liberan 4 H[Author ID1: at Tue Aug 28 14:34:00 2001]+[Author ID1: at Tue Aug 28 14:34:00 2001] y 4 e[Author ID1: at Tue Aug 28 14:34:00 2001]-[Author ID1: at Tue Aug 28 14:34:00 2001] y una molécula de [Author ID1: at Tue Aug 28 14:34:00 2001]O[Author ID1: at Tue Aug 28 14:36:00 2001]2[Author ID1: at Tue Aug 28 14:36:00 2001] para [Author ID1: at Tue Aug 28 14:36:00 2001]transferir[Author ID1: at Tue Aug 28 14:37:00 2001] los 4 e[Author ID1: at Tue Aug 28 14:36:00 2001]-[Author ID1: at Tue Aug 28 14:36:00 2001] al NADPH se requieren un [Author ID1: at Tue Aug 28 14:36:00 2001]mínimo[Author ID1: at Tue Aug 28 14:37:00 2001] de 8 fotones.[Author ID1: at Tue Aug 28 14:36:00 2001] [Author ID1: at Tue Aug 28 14:35:00 2001][Author ID0: at ]

    Experimentalmente se requieren 8-10 fotones.[Author ID1: at Tue Aug 28 18:43:00 2001]

    El NADPH y el ATP son [Author ID1: at Tue Aug 28 18:44:00 2001]usados[Author ID1: at Tue Aug 28 18:45:00 2001] en reacciones bioquímicas ara reducir al O[Author ID1: at Tue Aug 28 18:44:00 2001]2[Author ID1: at Tue Aug 28 18:45:00 2001] y CH[Author ID1: at Tue Aug 28 18:45:00 2001]2[Author ID1: at Tue Aug 28 18:45:00 2001]O.[Author ID0: at ]

    Mientras q la fase luminosa ocurre en 10[Author ID1: at Tue Aug 28 18:45:00 2001]-12[Author ID1: at Tue Aug 28 18:45:00 2001] sg, la fase oscura es [Author ID1: at Tue Aug 28 18:45:00 2001]más[Author ID1: at Tue Aug 28 19:52:00 2001] lenta.[Author ID1: at Tue Aug 28 18:45:00 2001]

    La entrada de [Author ID1: at Tue Aug 28 18:46:00 2001]energía[Author ID1: at Tue Aug 28 19:00:00 2001] requiere la participación de dos procesos fotoquímicos encargados de obtener la [Author ID1: at Tue Aug 28 18:46:00 2001]energía[Author ID1: at Tue Aug 28 18:50:00 2001] (PS)[Author ID1: at Tue Aug 28 18:46:00 2001][Author ID1: at Tue Aug 28 18:48:00 2001]

    -->Rendimiento cu[Author ID1: at Tue Aug 28 18:48:00 2001][Author ID1: at Tue Aug 28 18:56:00 2001]-->á[Author ID1: at Tue Aug 28 18:50:00 2001][Author ID1: at Tue Aug 28 18:56:00 2001]-->ntico[Author ID1: at Tue Aug 28 18:48:00 2001][Author ID1: at Tue Aug 28 18:56:00 2001]--> [Author ID1: at Tue Aug 28 18:49:00 2001][Author ID1: at Tue Aug 28 18:56:00 2001]-->=[Author ID1: at Tue Aug 28 18:51:00 2001][Author ID1: at Tue Aug 28 18:56:00 2001] desprendimiento de O[Author ID1: at Tue Aug 28 18:51:00 2001]2[Author ID1: at Tue Aug 28 18:54:00 2001] frente a destellos[Author ID1: at Tue Aug 28 18:54:00 2001] de longitud de onda variable entre [Author ID1: at Tue Aug 28 18:55:00 2001]400-680 nm, el rendimiento cu[Author ID1: at Tue Aug 28 18:55:00 2001]á[Author ID1: at Tue Aug 28 18:56:00 2001]ntico es el mismo. A partir de 680 nm se da [Author ID1: at Tue Aug 28 18:55:00 2001]una[Author ID1: at Tue Aug 28 18:57:00 2001] [Author ID1: at Tue Aug 28 18:55:00 2001]caída[Author ID1: at Tue Aug 28 18:56:00 2001] del rendimiento cu[Author ID1: at Tue Aug 28 18:55:00 2001]á[Author ID1: at Tue Aug 28 18:57:00 2001]ntico de la[Author ID1: at Tue Aug 28 18:55:00 2001] fotosíntesis.[Author ID1: at Tue Aug 28 18:56:00 2001][Author ID1: at Tue Aug 28 19:00:00 2001]

    Efecto intensificador o efecto Emerson =[Author ID1: at Tue Aug 28 19:00:00 2001] al analizar la tasa [Author ID1: at Tue Aug 28 19:00:00 2001]metabólica en función de [Author ID1: at Tue Aug 28 19:01:00 2001][Author ID1: at Tue Aug 28 19:04:00 2001] distintas observo q al aplicar [Author ID1: at Tue Aug 28 19:04:00 2001]simultán[Author ID1: at Tue Aug 28 19:07:00 2001]eamente[Author ID1: at Tue Aug 28 19:07:00 2001] superior a 700 nm e inferior a700 nm, la tasa [Author ID1: at Tue Aug 28 19:05:00 2001]fotosintética[Author ID1: at Tue Aug 28 19:07:00 2001] era superior q al aplicarlas por separado.[Author ID1: at Tue Aug 28 19:05:00 2001][Author ID0: at ]

    Esto llevo a determinar la existencia del PS II ([Author ID1: at Tue Aug 28 19:06:00 2001]absorbe[Author ID1: at Tue Aug 28 19:07:00 2001] [Author ID1: at Tue Aug 28 19:06:00 2001]radiación hasta 680 nm) y del PS I (absorbe radiación superior a 700 nm)[Author ID1: at Tue Aug 28 19:07:00 2001].[Author ID0: at ]

    [Author ID1: at Tue Aug 28 19:08:00 2001]Así[Author ID1: at Tue Aug 28 19:11:00 2001] como consecuencia de la absorción del PS I se da la existencia de un agente reductor fuerte y un oxidante [Author ID1: at Tue Aug 28 19:08:00 2001]débil[Author ID1: at Tue Aug 28 19:11:00 2001] (oxida al [Author ID1: at Tue Aug 28 19:08:00 2001]citocromo[Author ID1: at Tue Aug 28 19:09:00 2001])[Author ID1: at Tue Aug 28 19:08:00 2001].[Author ID1: at Tue Aug 28 19:09:00 2001]

    Cuando [Author ID1: at Tue Aug 28 19:10:00 2001]absorbe[Author ID1: at Tue Aug 28 19:11:00 2001] el PS II se origina un agente reductor [Author ID1: at Tue Aug 28 19:10:00 2001]débil[Author ID1: at Tue Aug 28 19:11:00 2001] (reduce al citocromo oxidado por el PS I y un agente oxidante fuerte capaz de o[Author ID1: at Tue Aug 28 19:10:00 2001]xidar al agua[Author ID1: at Tue Aug 28 19:11:00 2001].[Author ID1: at Tue Aug 28 19:36:00 2001][Author ID0: at ]

    A partir de estos experimentos se determina la existencia de dos[Author ID1: at Tue Aug 28 19:12:00 2001] proceso fotoquímicos ligados al PS I y[Author ID1: at Tue Aug 28 19:13:00 2001] [Author ID1: at Tue Aug 28 19:36:00 2001]PS II q [Author ID1: at Tue Aug 28 19:13:00 2001]actúan[Author ID1: at Tue Aug 28 19:36:00 2001] en serie (esquema Z[Author ID1: at Tue Aug 28 19:13:00 2001]).[Author ID1: at Tue Aug 28 19:36:00 2001] [Author ID1: at Tue Aug 28 19:13:00 2001]Este proceso de transferencia electrónica es [Author ID1: at Tue Aug 28 19:15:00 2001]típico[Author ID1: at Tue Aug 28 19:36:00 2001] y exclusivo de planta[Author ID1: at Tue Aug 28 19:15:00 2001]s superiores y algas verde azulada (las bacterias fotosintéticas poseen solo un fotosistema)[Author ID0: at ]

    La [Author ID1: at Tue Aug 28 19:16:00 2001]energía[Author ID1: at Tue Aug 28 19:37:00 2001] de la luz es captada por los [Author ID1: at Tue Aug 28 19:16:00 2001]sistemas[Author ID1: at Tue Aug 28 19:37:00 2001] colectores de [Author ID1: at Tue Aug 28 19:16:00 2001]radiación[Author ID1: at Tue Aug 28 19:17:00 2001] [Author ID1: at Tue Aug 28 19:16:00 2001] que son [Author ID1: at Tue Aug 28 19:17:00 2001]el[Author ID1: at Tue Aug 28 19:38:00 2001] sistema antena y se canalizan a los centros de [Author ID1: at Tue Aug 28 19:17:00 2001]reacción[Author ID1: at Tue Aug 28 19:37:00 2001] de los PS, d[Author ID1: at Tue Aug 28 19:17:00 2001]í[Author ID1: at Tue Aug 28 19:37:00 2001]mero especial de clorofila[Author ID1: at Tue Aug 28 19:17:00 2001].[Author ID1: at Tue Aug 28 19:18:00 2001]

    (Hoja 29 [Author ID1: at Tue Aug 28 19:18:00 2001]Fig.[Author ID1: at Tue Aug 28 19:19:00 2001] 2 [Author ID1: at Tue Aug 28 19:18:00 2001]y 65) [Author ID1: at Tue Aug 28 19:19:00 2001]La [Author ID1: at Tue Aug 28 19:19:00 2001]energía[Author ID1: at Tue Aug 28 19:38:00 2001] q llega al PS es [Author ID1: at Tue Aug 28 19:19:00 2001]energía[Author ID1: at Tue Aug 28 19:38:00 2001] captada[Author ID1: at Tue Aug 28 19:19:00 2001] por los sistemas antena. La [Author ID1: at Tue Aug 28 19:20:00 2001]energía[Author ID1: at Tue Aug 28 19:38:00 2001] de excitación se transfiere desde las moléculas de pigmento a moléculas adyacentes con [Author ID1: at Tue Aug 28 19:20:00 2001]máximos[Author ID1: at Tue Aug 28 19:21:00 2001] [Author ID1: at Tue Aug 28 19:20:00 2001]de absorción superiores (menos energéticos) transmitiendo la [Author ID1: at Tue Aug 28 19:21:00 2001]energía[Author ID1: at Tue Aug 28 19:38:00 2001] a los centros de [Author ID1: at Tue Aug 28 19:21:00 2001]reacción[Author ID1: at Tue Aug 28 19:38:00 2001].[Author ID1: at Tue Aug 28 19:21:00 2001]

    (Hoja 30 [Author ID1: at Tue Aug 28 19:21:00 2001]Fig.[Author ID1: at Tue Aug 28 19:38:00 2001] 8.21) [Author ID1: at Tue Aug 28 19:21:00 2001]Durante este [Author ID1: at Tue Aug 28 19:22:00 2001]proceso[Author ID1: at Tue Aug 28 19:38:00 2001] de transferencia hay carotenoides, clorofila a y b q realizan un [Author ID1: at Tue Aug 28 19:22:00 2001]movimiento[Author ID1: at Tue Aug 28 19:38:00 2001] hacia abajo ([Author ID1: at Tue Aug 28 19:22:00 2001]direccional[Author ID1: at Tue Aug 28 19:38:00 2001] e irreversible) con perdida[Author ID1: at Tue Aug 28 19:22:00 2001]s de calor [Author ID1: at Tue Aug 28 19:23:00 2001]mínimas[Author ID1: at Tue Aug 28 19:38:00 2001]. Es un proceso muy eficiente.[Author ID1: at Tue Aug 28 19:23:00 2001]

    -->([Author ID1: at Tue Aug 28 19:23:00 2001][Author ID1: at Tue Aug 28 19:35:00 2001]-->Fig.[Author ID1: at Tue Aug 28 19:38:00 2001][Author ID1: at Tue Aug 28 19:35:00 2001]--> 8.22)[Author ID1: at Tue Aug 28 19:23:00 2001][Author ID1: at Tue Aug 28 19:35:00 2001] Existe una heterogeneidad lateral entre ambos PS. [Author ID1: at Tue Aug 28 19:23:00 2001]Existen tilacoides granales y estromales, afecta a la capacidad del sistema para [Author ID1: at Tue Aug 28 19:24:00 2001]distribuir[Author ID1: at Tue Aug 28 19:38:00 2001] la [Author ID1: at Tue Aug 28 19:24:00 2001]energía[Author ID1: at Tue Aug 28 19:38:00 2001] entre [Author ID1: at Tue Aug 28 19:24:00 2001]ambos[Author ID1: at Tue Aug 28 19:38:00 2001] fotosistemas.[Author ID1: at Tue Aug 28 19:24:00 2001]

    La [Author ID1: at Tue Aug 28 19:25:00 2001]fotosíntesis[Author ID1: at Tue Aug 28 19:38:00 2001] en plantas superiores depende de dos PS con distintas [Author ID1: at Tue Aug 28 19:25:00 2001]propiedades[Author ID1: at Tue Aug 28 19:26:00 2001].[Author ID1: at Tue Aug 28 19:25:00 2001][Author ID0: at ]

    Presenta un problema para el sistema: si la tasa de absorción de [Author ID1: at Tue Aug 28 19:26:00 2001]energía[Author ID1: at Tue Aug 28 19:38:00 2001] no esta balanceada, todo el proceso [Author ID1: at Tue Aug 28 19:26:00 2001]fotosintético[Author ID1: at Tue Aug 28 19:27:00 2001] [Author ID1: at Tue Aug 28 19:26:00 2001]estará[Author ID1: at Tue Aug 28 19:38:00 2001] limitado por el proceso q reciba menor [Author ID1: at Tue Aug 28 19:27:00 2001]energía[Author ID1: at Tue Aug 28 19:38:00 2001]. [Author ID1: at Tue Aug 28 19:27:00 2001]Así[Author ID1: at Tue Aug 28 19:39:00 2001] las plantas de[Author ID1: at Tue Aug 28 19:27:00 2001]b[Author ID1: at Tue Aug 28 19:39:00 2001]en conseguir q se equilibre el aporte de [Author ID1: at Tue Aug 28 19:27:00 2001]energía[Author ID1: at Tue Aug 28 19:38:00 2001] mediante [Author ID1: at Tue Aug 28 19:27:00 2001]trasvase[Author ID1: at Tue Aug 28 19:39:00 2001] de la [Author ID1: at Tue Aug 28 19:27:00 2001]energía[Author ID1: at Tue Aug 28 19:38:00 2001] desde la zona de [Author ID1: at Tue Aug 28 19:27:00 2001]tilacoides[Author ID1: at Tue Aug 28 19:28:00 2001] [Author ID1: at Tue Aug 28 19:27:00 2001]granales del PS II a los tilacoides estromales del PS I.[Author ID1: at Tue Aug 28 19:28:00 2001][Author ID0: at ]

    En este proceso en un principio hay una situación donde el PS II recibe [Author ID1: at Tue Aug 28 19:29:00 2001]energía[Author ID1: at Tue Aug 28 19:38:00 2001] de LHC II y la PS I recibe menos [Author ID1: at Tue Aug 28 19:29:00 2001]energía[Author ID1: at Tue Aug 28 19:38:00 2001]. [Author ID1: at Tue Aug 28 19:29:00 2001]En las membranas del Tilacoide hay proteinkinasas q fosforilan las [Author ID1: at Tue Aug 28 19:30:00 2001]proteínas[Author ID1: at Tue Aug 28 19:39:00 2001] del sistema captador de [Author ID1: at Tue Aug 28 19:30:00 2001]energía[Author ID1: at Tue Aug 28 19:38:00 2001] (residuo de treonina).[Author ID1: at Tue Aug 28 19:30:00 2001]

    Como consecuencia se produce un desplazamiento motivado por el rechazo de cargas del mismo signo de [Author ID1: at Tue Aug 28 19:31:00 2001]proteína[Author ID1: at Tue Aug 28 19:39:00 2001] adyacentes desde la zona granal a la estromal ([Author ID1: at Tue Aug 28 19:31:00 2001]redistribución[Author ID1: at Tue Aug 28 19:39:00 2001] de la [Author ID1: at Tue Aug 28 19:31:00 2001]energía[Author ID1: at Tue Aug 28 19:38:00 2001] de ambos fotosistemas).[Author ID1: at Tue Aug 28 19:31:00 2001]

    Cuando hay de nuevo [Author ID1: at Tue Aug 28 19:32:00 2001]descompensación[Author ID1: at Tue Aug 28 19:39:00 2001] se activa la fosfatasa q desfosforila las treoninas desplazando el complejo antena de la zona estromal a la granal.[Author ID1: at Tue Aug 28 19:32:00 2001]

    La señal de [Author ID1: at Tue Aug 28 19:33:00 2001]activación[Author ID1: at Tue Aug 28 19:40:00 2001] de la proteinkinasa de la membrana de los tilac[Author ID1: at Tue Aug 28 19:33:00 2001]o[Author ID1: at Tue Aug 28 19:40:00 2001]ides es el estado de [Author ID1: at Tue Aug 28 19:33:00 2001]reducción[Author ID1: at Tue Aug 28 19:34:00 2001] [Author ID1: at Tue Aug 28 19:33:00 2001]de un [Author ID1: at Tue Aug 28 19:34:00 2001]intermediario[Author ID1: at Tue Aug 28 19:40:00 2001] de la CTE, la plastoquinona[Author ID1: at Tue Aug 28 19:34:00 2001]-->.[Author ID1: at Tue Aug 28 19:34:00 2001][Author ID1: at Tue Aug 28 19:35:00 2001] [Author ID1: at Tue Aug 28 19:35:00 2001]-->(Hoja 31 [Author ID1: at Tue Aug 28 19:34:00 2001][Author ID1: at Tue Aug 28 19:35:00 2001]-->Fig.[Author ID1: at Tue Aug 28 19:38:00 2001][Author ID1: at Tue Aug 28 19:35:00 2001]--> 4.15)[Author ID1: at Tue Aug 28 19:34:00 2001][Author ID1: at Tue Aug 28 19:35:00 2001].[Author ID1: at Tue Aug 28 20:29:00 2001]

    -->Si hay descompensación de entrada de luz frente al PS I del PS II, los e[Author ID1: at Tue Aug 28 20:29:00 2001][Author ID1: at Tue Aug 28 20:29:00 2001]-[Author ID1: at Tue Aug 28 20:30:00 2001] procedentes del agua llegan a la plastoquinona oxidada y la reducen.[Author ID0: at ]

    Para [Author ID1: at Tue Aug 28 20:30:00 2001]volver[Author ID1: at Tue Aug 28 20:31:00 2001] a recibir e[Author ID1: at Tue Aug 28 20:30:00 2001]-[Author ID1: at Tue Aug 28 20:31:00 2001] la reoxida el PS I para llevarlos al NADPH. Se produce una acumulación de plastoquinona reducida. [Author ID1: at Tue Aug 28 20:31:00 2001]Q la tiene disipar por calor, fluorescencia...[Author ID0: at ]

    Este acumulo activa la proteinkinasa para q oxide las treoninas desplazando los sistemas antena desde el estroma a los grana.[Author ID1: at Tue Aug 28 20:32:00 2001]

    Cuando los niveles [Author ID1: at Tue Aug 28 20:33:00 2001]están[Author ID1: at Tue Aug 28 20:34:00 2001] balanceados la plastoquinona reducida baja, y se activa una fosfatasa q desfosforila la [Author ID1: at Tue Aug 28 20:33:00 2001]treonina[Author ID1: at Tue Aug 28 20:34:00 2001],[Author ID1: at Tue Aug 28 20:33:00 2001] y puede regresar de nuevo el sistema de una zona a otra.[Author ID1: at Tue Aug 28 20:34:00 2001][Author ID1: at Thu Aug 30 20:52:00 2001]

    [Author ID0: at ]

    [Author ID1: at Thu Aug 30 20:42:00 2001]

    -->Tema 7 mecanismos de transporte de [Author ID1: at Thu Aug 30 20:42:00 2001][Author ID1: at Fri Aug 31 14:44:00 2001]-->electrones [Author ID1: at Thu Aug 30 21:12:00 2001][Author ID1: at Fri Aug 31 14:44:00 2001]-->y [Author ID1: at Thu Aug 30 20:42:00 2001][Author ID1: at Fri Aug 31 14:44:00 2001]-->protones[Author ID1: at Thu Aug 30 20:43:00 2001][Author ID1: at Fri Aug 31 14:44:00 2001]

    -->[Author ID1: at Thu Aug 30 20:43:00 2001][Author ID1: at Sun Sep 2 17:23:00 2001]

    [Author ID1: at Thu Aug 30 20:47:00 2001]

    (Hoja 32 [Author ID1: at Thu Aug 30 20:43:00 2001]Fig.[Author ID1: at Thu Aug 30 20:45:00 2001] 8.25)[Author ID1: at Thu Aug 30 20:43:00 2001] Hay 4 complejos:[Author ID0: at ]

    [Author ID1: at Thu Aug 30 20:51:00 2001]

    -->[Author ID1: at Thu Aug 30 20:42:00 2001][Author ID1: at Thu Aug 30 20:43:00 2001]

    (Hoja 33 [Author ID1: at Thu Aug 30 20:52:00 2001]Fig.[Author ID1: at Thu Aug 30 21:46:00 2001] 13.4)[Author ID1: at Thu Aug 30 20:52:00 2001] Estos complejos [Author ID1: at Thu Aug 30 20:53:00 2001]están[Author ID1: at Thu Aug 30 20:54:00 2001] vectorialmente en la membrana q provoca una diferencia de carga [Author ID1: at Thu Aug 30 20:53:00 2001]eléctrica[Author ID1: at Thu Aug 30 20:54:00 2001] (+ en el interior y [Author ID1: at Thu Aug 30 20:53:00 2001]-[Author ID1: at Thu Aug 30 20:54:00 2001] en [Author ID1: at Thu Aug 30 20:53:00 2001]el lumen por la descarga de H[Author ID1: at Thu Aug 30 20:54:00 2001]+[Author ID1: at Thu Aug 30 20:55:00 2001])[Author ID1: at Thu Aug 30 20:55:00 2001]

    E[Author ID1: at Thu Aug 30 20:57:00 2001]l primer paso del [Author ID1: at Thu Aug 30 20:55:00 2001]almacenamiento[Author ID1: at Thu Aug 30 21:46:00 2001] de la [Author ID1: at Thu Aug 30 20:55:00 2001]energía[Author ID1: at Thu Aug 30 21:46:00 2001] en el sistema se produce a nivel del centro de [Author ID1: at Thu Aug 30 20:55:00 2001]reacción[Author ID1: at Thu Aug 30 21:46:00 2001] del PS II,[Author ID1: at Thu Aug 30 20:55:00 2001] molécula de [Author ID1: at Thu Aug 30 20:56:00 2001]clorofila[Author ID1: at Thu Aug 30 21:46:00 2001] P[Author ID1: at Thu Aug 30 20:56:00 2001]680[Author ID1: at Thu Aug 30 20:56:00 2001] [Author ID1: at Thu Aug 30 20:56:00 2001](Hoja 34 [Author ID1: at Thu Aug 30 20:56:00 2001]Fig.[Author ID1: at Thu Aug 30 20:57:00 2001] 8.27)[Author ID1: at Thu Aug 30 20:56:00 2001][Author ID0: at ]

    Esta[Author ID1: at Thu Aug 30 20:57:00 2001] captación directa o a [Author ID1: at Thu Aug 30 20:58:00 2001]través[Author ID1: at Thu Aug 30 21:46:00 2001] de pigmento antena, excita la molécula de clorofila, un e[Author ID1: at Thu Aug 30 20:58:00 2001]-[Author ID1: at Thu Aug 30 20:58:00 2001] se lanza del orbital basal a otro [Author ID1: at Thu Aug 30 20:58:00 2001]más[Author ID1: at Mon Sep 3 15:36:00 2001] externo, este e[Author ID1: at Thu Aug 30 20:58:00 2001]-[Author ID1: at Thu Aug 30 20:59:00 2001] excitado esta [Author ID1: at Thu Aug 30 20:59:00 2001]más[Author ID1: at Mon Sep 3 15:36:00 2001] débilmente retenido por fuerzas de atracción de cargas +del [Author ID1: at Thu Aug 30 20:59:00 2001]núcleo[Author ID1: at Thu Aug 30 21:00:00 2001].[Author ID1: at Thu Aug 30 20:59:00 2001][Author ID0: at ]

    La molécula de clorofila en estado [Author ID1: at Thu Aug 30 21:00:00 2001]excitado[Author ID1: at Thu Aug 30 21:04:00 2001] se convierte en una molécula [Author ID1: at Thu Aug 30 21:00:00 2001]más[Author ID1: at Mon Sep 3 15:36:00 2001] reductora. El e[Author ID1: at Thu Aug 30 21:00:00 2001]-[Author ID1: at Thu Aug 30 21:00:00 2001] tiene dos posibilidades:[Author ID1: at Thu Aug 30 21:01:00 2001]

    Así[Author ID1: at Thu Aug 30 21:47:00 2001] la molécula de clorofila posee un hueco [Author ID1: at Thu Aug 30 21:05:00 2001]electrónico[Author ID1: at Thu Aug 30 21:46:00 2001] q se rellena por e[Author ID1: at Thu Aug 30 21:05:00 2001]-[Author ID1: at Thu Aug 30 21:05:00 2001] cedidos por el donador 1º q lo recibe de un donador 2º y el ultimo donador es el agua.[Author ID1: at Thu Aug 30 21:05:00 2001]

    Cuando la clorofila pierde un e[Author ID1: at Thu Aug 30 21:06:00 2001]-[Author ID1: at Thu Aug 30 21:07:00 2001] la molécula esta en estado oxidado, [Author ID1: at Thu Aug 30 21:07:00 2001]varían[Author ID1: at Thu Aug 30 21:47:00 2001] las características espectrales de absorción del rojo y estos picos se ven disminuidos cuando se oxidan.[Author ID1: at Thu Aug 30 21:07:00 2001][Author ID0: at ]

    KoK [Author ID1: at Thu Aug 30 21:08:00 2001]encontró[Author ID1: at Thu Aug 30 21:47:00 2001] el centro de [Author ID1: at Thu Aug 30 21:08:00 2001]reacción[Author ID1: at Thu Aug 30 21:47:00 2001] 1º con un [Author ID1: at Thu Aug 30 21:08:00 2001]máximo[Author ID1: at Thu Aug 30 21:09:00 2001] [Author ID1: at Thu Aug 30 21:08:00 2001]de absorción de 700 nm y lo denomino P[Author ID1: at Thu Aug 30 21:09:00 2001]700[Author ID1: at Thu Aug 30 21:09:00 2001].[Author ID0: at ]

    Witt [Author ID1: at Thu Aug 30 21:09:00 2001]observó[Author ID1: at Thu Aug 30 21:47:00 2001] una [Author ID1: at Thu Aug 30 21:09:00 2001]absorción[Author ID1: at Thu Aug 30 21:10:00 2001] [Author ID1: at Thu Aug 30 21:09:00 2001]de 680 nm y lo denominó P[Author ID1: at Thu Aug 30 21:10:00 2001]680[Author ID1: at Thu Aug 30 21:10:00 2001], era el centro de [Author ID1: at Thu Aug 30 21:10:00 2001]reacción[Author ID1: at Thu Aug 30 21:47:00 2001] 2º.[Author ID1: at Thu Aug 30 21:10:00 2001][Author ID0: at ]

    Dnysens [Author ID1: at Thu Aug 30 21:13:00 2001]trabajando con bacterias fotosintéticas [Author ID1: at Thu Aug 30 21:14:00 2001]estableció[Author ID1: at Thu Aug 30 21:17:00 2001] q el centro de [Author ID1: at Thu Aug 30 21:14:00 2001]reacción[Author ID1: at Thu Aug 30 21:47:00 2001] de bacterias con clorofila tiene un [Author ID1: at Thu Aug 30 21:14:00 2001]máximo[Author ID1: at Thu Aug 30 21:15:00 2001] [Author ID1: at Thu Aug 30 21:14:00 2001]de absorción a 870 nm y lo llamo P[Author ID1: at Thu Aug 30 21:15:00 2001]870[Author ID1: at Thu Aug 30 21:15:00 2001].[Author ID0: at ]

    Por rayos X [Author ID1: at Thu Aug 30 21:15:00 2001]estableció[Author ID1: at Thu Aug 30 21:17:00 2001] q es un d[Author ID1: at Thu Aug 30 21:15:00 2001]í[Author ID1: at Thu Aug 30 21:17:00 2001]mero de [Author ID1: at Thu Aug 30 21:15:00 2001]bacterioclorofila[Author ID1: at Thu Aug 30 21:16:00 2001].[Author ID1: at Thu Aug 30 21:15:00 2001] Análisis semejantes determinaron q el PS I es un d[Author ID1: at Thu Aug 30 21:16:00 2001]í[Author ID1: at Thu Aug 30 21:17:00 2001]mero de P[Author ID1: at Thu Aug 30 21:16:00 2001]700[Author ID1: at Thu Aug 30 21:16:00 2001]. existen [Author ID1: at Thu Aug 30 21:16:00 2001]más[Author ID1: at Mon Sep 3 15:36:00 2001] dudas del estado de [Author ID1: at Thu Aug 30 21:16:00 2001]agregación[Author ID1: at Thu Aug 30 21:17:00 2001] del PS II.[Author ID1: at Thu Aug 30 21:16:00 2001][Author ID1: at Thu Aug 30 21:17:00 2001]

    (Hoja 34 [Author ID1: at Thu Aug 30 21:17:00 2001]Fig.[Author ID1: at Thu Aug 30 21:47:00 2001] 8.26)[Author ID1: at Thu Aug 30 21:17:00 2001] El hueco electrónico de ceder los e[Author ID1: at Thu Aug 30 21:18:00 2001]-[Author ID1: at Thu Aug 30 21:18:00 2001] va a ser rellenado por e[Author ID1: at Thu Aug 30 21:18:00 2001]-[Author ID1: at Thu Aug 30 21:19:00 2001] de l fotolisis del agua.[Author ID0: at ]

    Todo el complejo es polipept[Author ID1: at Thu Aug 30 21:19:00 2001]í[Author ID1: at Thu Aug 30 21:47:00 2001]dico, tiene P[Author ID1: at Thu Aug 30 21:19:00 2001]680[Author ID1: at Thu Aug 30 21:19:00 2001], [Author ID1: at Thu Aug 30 21:19:00 2001]feofitina[Author ID1: at Thu Aug 30 21:20:00 2001],[Author ID1: at Thu Aug 30 21:19:00 2001] varias quinonas asociadas al centro de [Author ID1: at Thu Aug 30 21:20:00 2001]reacción[Author ID1: at Thu Aug 30 21:47:00 2001] q a su vez consta de varias [Author ID1: at Thu Aug 30 21:20:00 2001]proteínas[Author ID1: at Thu Aug 30 21:47:00 2001]; fundamentalmente estas [Author ID1: at Thu Aug 30 21:20:00 2001]proteínas[Author ID1: at Thu Aug 30 21:47:00 2001] tienen un Pm de 32 y 34 Kda,[Author ID1: at Thu Aug 30 21:20:00 2001] conocidas como [Author ID1: at Thu Aug 30 21:21:00 2001]proteínas[Author ID1: at Thu Aug 30 21:47:00 2001] D[Author ID1: at Thu Aug 30 21:21:00 2001]1[Author ID1: at Thu Aug 30 21:21:00 2001] y D[Author ID1: at Thu Aug 30 21:21:00 2001]2[Author ID1: at Thu Aug 30 21:21:00 2001] respectivamente y existen otras [Author ID1: at Thu Aug 30 21:21:00 2001]proteínas[Author ID1: at Thu Aug 30 21:47:00 2001] de Pm 33, 23 y 16 Kda [Author ID1: at Thu Aug 30 21:21:00 2001]al q [Author ID1: at Thu Aug 30 21:22:00 2001]están[Author ID1: at Thu Aug 30 21:47:00 2001] ligados el sistema [Author ID1: at Thu Aug 30 21:22:00 2001]enzimático[Author ID1: at Thu Aug 30 21:47:00 2001] q produce la fotolisis del agua.[Author ID1: at Thu Aug 30 21:22:00 2001]

    La [Author ID1: at Thu Aug 30 21:23:00 2001]reacción[Author ID1: at Thu Aug 30 21:47:00 2001] química por la q se oxida el agua consiste en la ruptura de 2 [Author ID1: at Thu Aug 30 21:23:00 2001]moléculas[Author ID1: at Thu Aug 30 21:48:00 2001] de agua para liberar un O[Author ID1: at Thu Aug 30 21:23:00 2001]2[Author ID1: at Thu Aug 30 21:24:00 2001], la acumulación de 4 H[Author ID1: at Thu Aug 30 21:26:00 2001]+[Author ID1: at Thu Aug 30 21:26:00 2001] en el lumen del Tilacoide y liberación de 4 e[Author ID1: at Thu Aug 30 21:26:00 2001]-[Author ID1: at Thu Aug 30 21:27:00 2001] transferidos a [Author ID1: at Thu Aug 30 21:27:00 2001]través[Author ID1: at Thu Aug 30 21:48:00 2001] de la CTE para dar 2 NADPH.[Author ID0: at ]

    Se conoce poco del mecanismo de ruptura del agua ligado al PS II.[Author ID1: at Thu Aug 30 21:27:00 2001]

    Existen pruebas indirectas sobre el proceso:[Author ID1: at Thu Aug 30 21:28:00 2001]

    Este [Author ID1: at Thu Aug 30 21:31:00 2001]mecanismo se h intentado explicar por el [Author ID1: at Thu Aug 30 21:32:00 2001]Modelo S de Kok.[Author ID1: at Thu Aug 30 21:32:00 2001] [Author ID1: at Thu Aug 30 21:32:00 2001]S[Author ID1: at Thu Aug 30 21:32:00 2001]1[Author ID1: at Thu Aug 30 21:32:00 2001], S[Author ID1: at Thu Aug 30 21:32:00 2001]2[Author ID1: at Thu Aug 30 21:32:00 2001], [Author ID1: at Thu Aug 30 21:32:00 2001]S[Author ID1: at Thu Aug 30 21:33:00 2001]3[Author ID1: at Thu Aug 30 21:33:00 2001], ...[Author ID1: at Thu Aug 30 21:33:00 2001][Author ID1: at Thu Aug 30 21:34:00 2001]

    El sistema lítico del agua atraviesa por etapas sucesivamente [Author ID1: at Thu Aug 30 21:34:00 2001]más[Author ID1: at Mon Sep 3 15:36:00 2001] oxidadas. Cuando [Author ID1: at Thu Aug 30 21:34:00 2001]pasa de un estado a otro implica la captación de un fot[Author ID1: at Thu Aug 30 21:35:00 2001]ó[Author ID1: at Thu Aug 30 21:48:00 2001]n. [Author ID1: at Thu Aug 30 21:35:00 2001](Hoja 35 [Author ID1: at Thu Aug 30 21:35:00 2001]Fig.[Author ID1: at Thu Aug 30 21:49:00 2001] 8.29)[Author ID1: at Thu Aug 30 21:35:00 2001]

    Se piensa q estos estados de [Author ID1: at Thu Aug 30 21:36:00 2001]oxidorreducción[Author ID1: at Thu Aug 30 21:49:00 2001] serian estados de oxidación de [Author ID1: at Thu Aug 30 21:36:00 2001]átomos[Author ID1: at Thu Aug 30 21:49:00 2001] de Mn q se sabe q forman parte del complejo del PS II.[Author ID1: at Thu Aug 30 21:36:00 2001]

    Los 4 Mn [Author ID1: at Thu Aug 30 21:37:00 2001]estarían[Author ID1: at Thu Aug 30 21:49:00 2001] sometidos a oxidaciones sucesivas pasando a tener distintos estados hasta llevarse a cabo la fotolisis del agua.[Author ID1: at Thu Aug 30 21:37:00 2001]

    En el sistema [Author ID1: at Thu Aug 30 21:38:00 2001]lítico[Author ID1: at Thu Aug 30 21:44:00 2001] del agua también existen [Author ID1: at Thu Aug 30 21:38:00 2001]átomos[Author ID1: at Thu Aug 30 21:44:00 2001] de Ca[Author ID1: at Thu Aug 30 21:38:00 2001]2+[Author ID1: at Thu Aug 30 21:38:00 2001] e iones Cl[Author ID1: at Thu Aug 30 21:38:00 2001]-[Author ID1: at Thu Aug 30 21:38:00 2001] cuyo papel no se conoce; se piensa q el Ca[Author ID1: at Thu Aug 30 21:38:00 2001]2+[Author ID1: at Thu Aug 30 21:39:00 2001] estabiliza las [Author ID1: at Thu Aug 30 21:39:00 2001]proteínas[Author ID1: at Thu Aug 30 21:44:00 2001] q se unen a los [Author ID1: at Thu Aug 30 21:39:00 2001]átomos[Author ID1: at Thu Aug 30 21:44:00 2001] de Mn.[Author ID0: at ]

    Los e[Author ID1: at Thu Aug 30 21:39:00 2001]-[Author ID1: at Thu Aug 30 21:39:00 2001]derivados de la ruptura del agua no pasan directamente al P[Author ID1: at Thu Aug 30 21:39:00 2001]680[Author ID1: at Thu Aug 30 21:40:00 2001], primero son cedidos a un componente [Author ID1: at Thu Aug 30 21:40:00 2001]más[Author ID1: at Mon Sep 3 15:37:00 2001] de la CTE q se llama componente Z Y[Author ID1: at Thu Aug 30 21:40:00 2001]z[Author ID1: at Thu Aug 30 21:42:00 2001] q es un residuo de Tyr de la propia [Author ID1: at Thu Aug 30 21:42:00 2001]proteína[Author ID1: at Thu Aug 30 21:44:00 2001] D[Author ID1: at Thu Aug 30 21:42:00 2001]1[Author ID1: at Thu Aug 30 21:43:00 2001] del centro de [Author ID1: at Thu Aug 30 21:43:00 2001]reacción[Author ID1: at Thu Aug 30 21:44:00 2001].[Author ID1: at Thu Aug 30 21:43:00 2001]-->[Author ID1: at Thu Aug 30 21:33:00 2001][Author ID1: at Thu Aug 30 21:43:00 2001]

    -->[Author ID1: at Thu Aug 30 21:16:00 2001][Author ID1: at Thu Aug 30 21:27:00 2001]

    -->[Author ID1: at Thu Aug 30 21:10:00 2001][Author ID1: at Thu Aug 30 21:16:00 2001]

    -->[Author ID1: at Thu Aug 30 21:03:00 2001][Author ID1: at Thu Aug 30 21:10:00 2001]

    -->[Author ID1: at Thu Aug 30 20:43:00 2001][Author ID1: at Thu Aug 30 20:57:00 2001]

    -->[Author ID1: at Tue Aug 28 18:56:00 2001][Author ID1: at Tue Aug 28 20:31:00 2001]

    [Author ID0: at ]

    [Author ID0: at ]

    [Author ID0: at ]

    [Author ID0: at ]

    [Author ID0: at ]

    [Author ID0: at ]

    [Author ID0: at ]

    [Author ID0: at ]

    El primer aceptor de e[Author ID1: at Thu Aug 30 22:14:00 2001]-[Author ID1: at Thu Aug 30 22:15:00 2001] es una feofitina q cede e[Author ID1: at Thu Aug 30 22:15:00 2001]-[Author ID1: at Thu Aug 30 22:15:00 2001] a las quinonas.[Author ID0: at ]

    La feofitina tiene sustituido el Mg por 2 H[Author ID1: at Thu Aug 30 22:15:00 2001]+[Author ID1: at Thu Aug 30 22:16:00 2001]. La [Author ID1: at Thu Aug 30 22:16:00 2001]energía[Author ID1: at Thu Aug 30 22:22:00 2001] redox de esta es distinta a la de la clorofila excitada par[Author ID1: at Thu Aug 30 22:16:00 2001]a ser [Author ID1: at Thu Aug 30 22:22:00 2001]capaz de captar la [Author ID1: at Thu Aug 30 22:16:00 2001]energía[Author ID1: at Thu Aug 30 22:21:00 2001] de la clorofila excitada. [Author ID1: at Thu Aug 30 22:16:00 2001]Esta cede e[Author ID1: at Thu Aug 30 22:17:00 2001]-[Author ID1: at Thu Aug 30 22:17:00 2001] a las quinonas, a la plastoquinona.[Author ID1: at Thu Aug 30 22:17:00 2001]

    ([Author ID1: at Thu Aug 30 22:17:00 2001]Fig.[Author ID1: at Thu Aug 30 22:21:00 2001] 8.30)[Author ID1: at Thu Aug 30 22:17:00 2001] Esta [Author ID1: at Thu Aug 30 22:17:00 2001]molécula[Author ID1: at Thu Aug 30 22:18:00 2001] [Author ID1: at Thu Aug 30 22:17:00 2001]funciona con 2 e[Author ID1: at Thu Aug 30 22:18:00 2001]-[Author ID1: at Thu Aug 30 22:18:00 2001] y 2 H[Author ID1: at Thu Aug 30 22:18:00 2001]+[Author ID1: at Thu Aug 30 22:18:00 2001] de [Author ID1: at Thu Aug 30 22:18:00 2001]modo[Author ID1: at Thu Aug 30 22:21:00 2001] q [Author ID1: at Thu Aug 30 22:18:00 2001]tenemos[Author ID1: at Thu Aug 30 22:21:00 2001] quinona oxidada, semioxidada y reducida.[Author ID1: at Thu Aug 30 22:18:00 2001]

    Tenemos una molécula de P[Author ID1: at Thu Aug 30 22:19:00 2001]680[Author ID1: at Thu Aug 30 22:19:00 2001], una Phe y dos quinonas A y B oxidadas en estado basal.[Author ID1: at Thu Aug 30 22:19:00 2001]

    Cuando P[Author ID1: at Thu Aug 30 22:20:00 2001]680[Author ID1: at Thu Aug 30 22:20:00 2001] recibe un fot[Author ID1: at Thu Aug 30 22:20:00 2001]ó[Author ID1: at Thu Aug 30 22:21:00 2001]n pierde 1 e[Author ID1: at Thu Aug 30 22:20:00 2001]-[Author ID1: at Thu Aug 30 22:20:00 2001]-->q pasa a Phe y este a la primera quinona quedando semirreducida.[Author ID1: at Thu Aug 30 22:20:00 2001][Author ID1: at Thu Aug 30 22:21:00 2001][Author ID0: at ]

    El e[Author ID1: at Thu Aug 30 22:22:00 2001]- [Author ID1: at Thu Aug 30 22:23:00 2001]-->de la primera quinona[Author ID1: at Thu Aug 30 22:23:00 2001][Author ID1: at Thu Aug 30 22:23:00 2001] es[Author ID1: at Thu Aug 30 22:24:00 2001]--> transferido a la segunda q es[Author ID1: at Thu Aug 30 22:23:00 2001][Author ID1: at Thu Aug 30 22:23:00 2001]ta semirreducida.[Author ID0: at ]

    Un pequeño destello provoca la perdida[Author ID1: at Thu Aug 30 22:24:00 2001] de un e[Author ID1: at Thu Aug 30 22:25:00 2001]-[Author ID1: at Thu Aug 30 22:25:00 2001] del P[Author ID1: at Thu Aug 30 22:25:00 2001]680[Author ID1: at Thu Aug 30 22:25:00 2001] llegando a [Author ID1: at Thu Aug 30 22:25:00 2001]tener[Author ID1: at Thu Aug 30 22:28:00 2001] las dos quinonas semirreducidas.[Author ID0: at ]

    El [Author ID1: at Thu Aug 30 22:25:00 2001]e[Author ID1: at Thu Aug 30 22:26:00 2001]-[Author ID1: at Thu Aug 30 22:26:00 2001] de la quinona A pasa a la B q toma H[Author ID1: at Thu Aug 30 22:26:00 2001]+[Author ID1: at Thu Aug 30 22:26:00 2001] del estroma transformándose en plastohidroquinona q traspasa la membrana tilacoidal y c[Author ID1: at Thu Aug 30 22:26:00 2001]ede los H[Author ID1: at Thu Aug 30 22:27:00 2001]+[Author ID1: at Thu Aug 30 22:27:00 2001] [Author ID1: at Thu Aug 30 22:28:00 2001]al lumen.[Author ID0: at ]

    Los e[Author ID1: at Thu Aug 30 22:27:00 2001]-[Author ID1: at Thu Aug 30 22:27:00 2001] de la plastohidroquinona pasan al complejo [Author ID1: at Thu Aug 30 22:27:00 2001]citocromo[Author ID1: at Thu Aug 30 22:28:00 2001] [Author ID1: at Thu Aug 30 22:27:00 2001]b[Author ID1: at Thu Aug 30 22:28:00 2001]6[Author ID1: at Sun Sep 2 17:28:00 2001] f.[Author ID1: at Thu Aug 30 22:28:00 2001][Author ID0: at ]

    Este es un complejo altamente [Author ID1: at Thu Aug 30 23:11:00 2001]polimérico[Author ID1: at Thu Aug 30 23:13:00 2001] con muchos grupos [Author ID1: at Thu Aug 30 23:11:00 2001]prostéticos[Author ID1: at Thu Aug 30 23:13:00 2001]: dos citocromo b y un [Author ID1: at Thu Aug 30 23:11:00 2001]citocromo[Author ID1: at Thu Aug 30 23:12:00 2001] [Author ID1: at Thu Aug 30 23:11:00 2001]c q como se [Author ID1: at Thu Aug 30 23:12:00 2001]descubrió[Author ID1: at Thu Aug 30 23:13:00 2001] primero en la [Author ID1: at Thu Aug 30 23:12:00 2001]hoja[Author ID1: at Thu Aug 30 23:13:00 2001] se denomino citocromo f. [Author ID1: at Thu Aug 30 23:12:00 2001](Hoja 36 [Author ID1: at Thu Aug 30 23:12:00 2001]Fig.[Author ID1: at Thu Aug 30 23:13:00 2001] 8.31)[Author ID1: at Thu Aug 30 23:12:00 2001]. este esta unido a residuos de cisteina de una [Author ID1: at Thu Aug 30 23:13:00 2001]proteína[Author ID1: at Fri Aug 31 01:15:00 2001]. [Author ID1: at Thu Aug 30 23:13:00 2001]Además[Author ID1: at Fri Aug 31 01:15:00 2001] [Author ID1: at Thu Aug 30 23:14:00 2001]existen[Author ID1: at Fri Aug 31 01:15:00 2001] [Author ID1: at Thu Aug 30 23:14:00 2001]proteínas[Author ID1: at Fri Aug 31 01:15:00 2001] de Rieske, sulfoprote[Author ID1: at Thu Aug 30 23:14:00 2001]í[Author ID1: at Fri Aug 31 01:16:00 2001]nas q tienen [Author ID1: at Thu Aug 30 23:14:00 2001]átomos[Author ID1: at Fri Aug 31 01:15:00 2001] de S unidos a [Author ID1: at Thu Aug 30 23:14:00 2001]átomos[Author ID1: at Fri Aug 31 01:15:00 2001] de Fe.[Author ID0: at ]

    La transferencia[Author ID1: at Thu Aug 30 23:14:00 2001] de e[Author ID1: at Fri Aug 31 01:16:00 2001]-[Author ID1: at Fri Aug 31 01:16:00 2001] a [Author ID1: at Fri Aug 31 01:16:00 2001]través[Author ID1: at Fri Aug 31 01:23:00 2001] del complejo cit b [Author ID1: at Fri Aug 31 01:16:00 2001]ó f se estudia mediante el [Author ID1: at Fri Aug 31 01:17:00 2001]Modelo del ciclo de las quinonas ([Author ID1: at Fri Aug 31 01:17:00 2001]Fig.[Author ID1: at Fri Aug 31 01:23:00 2001] 8.32).[Author ID1: at Fri Aug 31 01:17:00 2001] según el modelo las plastohidroquinonas ceden un e[Author ID1: at Fri Aug 31 01:18:00 2001]-[Author ID1: at Fri Aug 31 01:18:00 2001] a la [Author ID1: at Fri Aug 31 01:18:00 2001]proteína[Author ID1: at Fri Aug 31 01:23:00 2001] de Rieske q a su vez lo cede al [Author ID1: at Fri Aug 31 01:18:00 2001]citocromo[Author ID1: at Fri Aug 31 01:19:00 2001] [Author ID1: at Fri Aug 31 01:18:00 2001]f q a su vez a [Author ID1: at Fri Aug 31 01:19:00 2001]través[Author ID1: at Fri Aug 31 01:23:00 2001] de la plastocianina los cede al P[Author ID1: at Fri Aug 31 01:19:00 2001]700[Author ID1: at Fri Aug 31 01:19:00 2001].[Author ID0: at ]

    El 2º e[Author ID1: at Fri Aug 31 01:19:00 2001]- [Author ID1: at Fri Aug 31 01:19:00 2001]-->es cedido a uno de los [Author ID1: at Fri Aug 31 01:19:00 2001][Author ID1: at Fri Aug 31 01:21:00 2001]-->citocromos b del complejo q a su [Author ID1: at Fri Aug 31 01:20:00 2001][Author ID1: at Fri Aug 31 01:21:00 2001]-->vez[Author ID1: at Fri Aug 31 01:23:00 2001][Author ID1: at Fri Aug 31 01:21:00 2001]--> lo cede a [Author ID1: at Fri Aug 31 01:20:00 2001][Author ID1: at Fri Aug 31 01:21:00 2001]-->través[Author ID1: at Fri Aug 31 01:23:00 2001][Author ID1: at Fri Aug 31 01:21:00 2001]--> del 2º citocromo b a una quinona oxidada pasando a estar semi[Author ID1: at Fri Aug 31 01:20:00 2001][Author ID1: at Fri Aug 31 01:21:00 2001]-->reducida.[Author ID1: at Fri Aug 31 01:21:00 2001][Author ID1: at Fri Aug 31 01:21:00 2001] Paralelamente con la [Author ID1: at Fri Aug 31 01:21:00 2001]cesión[Author ID1: at Fri Aug 31 01:23:00 2001] de los 2 e[Author ID1: at Fri Aug 31 01:21:00 2001]-[Author ID1: at Fri Aug 31 01:21:00 2001] se produce la liberación de 2 [Author ID1: at Fri Aug 31 01:21:00 2001]H[Author ID1: at Fri Aug 31 01:22:00 2001]+[Author ID1: at Fri Aug 31 01:22:00 2001] en el lumen del Tilacoide.[Author ID0: at ]

    En una 2ª[Author ID1: at Fri Aug 31 01:22:00 2001] [Author ID1: at Fri Aug 31 01:23:00 2001]etapa una 2ª[Author ID1: at Fri Aug 31 01:22:00 2001] [Author ID1: at Fri Aug 31 01:23:00 2001]plastohidroquinona cede e[Author ID1: at Fri Aug 31 01:22:00 2001]-[Author ID1: at Fri Aug 31 01:23:00 2001] al PS I por el mismo ciclo y un 2º e[Author ID1: at Fri Aug 31 01:24:00 2001]-[Author ID1: at Fri Aug 31 01:24:00 2001] a [Author ID1: at Fri Aug 31 01:24:00 2001]través[Author ID1: at Fri Aug 31 01:45:00 2001] de los dos [Author ID1: at Fri Aug 31 01:24:00 2001]citocromos[Author ID1: at Fri Aug 31 01:25:00 2001] [Author ID1: at Fri Aug 31 01:24:00 2001]a la semiquinona anterior para completar la [Author ID1: at Fri Aug 31 01:25:00 2001]reducción[Author ID1: at Fri Aug 31 01:45:00 2001] de la quinona.[Author ID0: at ]

    Dos hidroquinonas se han oxidado a quinonas, una quinona [Author ID1: at Fri Aug 31 01:25:00 2001]se[Author ID1: at Fri Aug 31 01:45:00 2001] reduce completamente a hidroquinona.[Author ID1: at Fri Aug 31 01:25:00 2001][Author ID0: at ]

    Dos e[Author ID1: at Fri Aug 31 01:26:00 2001]-[Author ID1: at Fri Aug 31 01:26:00 2001] han sido transferidos al PS I. [Author ID1: at Fri Aug 31 01:26:00 2001]La transferencia de los e[Author ID1: at Fri Aug 31 01:27:00 2001]-[Author ID1: at Fri Aug 31 01:27:00 2001] ha sido acompañada por la liberación de 4 H[Author ID1: at Fri Aug 31 01:27:00 2001]+[Author ID1: at Fri Aug 31 01:27:00 2001] al lumen.[Author ID1: at Fri Aug 31 01:27:00 2001]

    Estos 4 H[Author ID1: at Fri Aug 31 01:28:00 2001]+[Author ID1: at Fri Aug 31 01:28:00 2001] con los de la fotolisis del agua constituyen el gradiente electroquímico q se establece entre el interior y [Author ID1: at Fri Aug 31 01:28:00 2001]exterior[Author ID1: at Fri Aug 31 01:29:00 2001] [Author ID1: at Fri Aug 31 01:28:00 2001]del estroma para la síntesis de ATP según la [Author ID1: at Fri Aug 31 01:29:00 2001]teoría[Author ID1: at Fri Aug 31 01:45:00 2001] de Mitchel.[Author ID0: at ]

    Dos H[Author ID1: at Fri Aug 31 01:29:00 2001]+[Author ID1: at Fri Aug 31 01:29:00 2001] se liberan al lumen la primera etapa y otros dos en la segunda etapa.[Author ID1: at Fri Aug 31 01:29:00 2001]

    La quinona se desplaza cíclicamente por la membrana de los [Author ID1: at Fri Aug 31 01:30:00 2001]tilacoides[Author ID1: at Fri Aug 31 01:31:00 2001].[Author ID1: at Fri Aug 31 01:30:00 2001][Author ID0: at ]

    En la cara estromal es [Author ID1: at Fri Aug 31 01:31:00 2001]donde[Author ID1: at Sun Sep 2 16:49:00 2001] toma los e[Author ID1: at Fri Aug 31 01:31:00 2001]-[Author ID1: at Fri Aug 31 01:31:00 2001] y en la cara luminal es [Author ID1: at Fri Aug 31 01:31:00 2001]donde[Author ID1: at Sun Sep 2 16:49:00 2001] cede los e[Author ID1: at Fri Aug 31 01:31:00 2001]-[Author ID1: at Fri Aug 31 01:31:00 2001].[Author ID0: at ]

    El [Author ID1: at Fri Aug 31 01:32:00 2001]-->transporte de e[Author ID1: at Fri Aug 31 01:32:00 2001][Author ID1: at Sun Sep 2 18:20:00 2001]-->-[Author ID1: at Fri Aug 31 01:32:00 2001][Author ID1: at Sun Sep 2 18:20:00 2001]--> [Author ID1: at Sun Sep 2 16:49:00 2001][Author ID1: at Sun Sep 2 18:20:00 2001]lineal[Author ID1: at Sun Sep 2 18:41:00 2001] (par[Author ID1: at Sun Sep 2 18:41:00 2001]a[Author ID1: at Mon Sep 3 16:04:00 2001] formar NADPH)[Author ID1: at Sun Sep 2 18:41:00 2001] se da[Author ID1: at Fri Aug 31 01:32:00 2001] [Author ID1: at Fri Aug 31 01:45:00 2001]cuando la [Author ID1: at Fri Aug 31 01:32:00 2001]plastocianina[Author ID1: at Fri Aug 31 01:35:00 2001] [Author ID1: at Fri Aug 31 01:32:00 2001]q es el [Author ID1: at Fri Aug 31 01:35:00 2001]siguiente[Author ID1: at Fri Aug 31 01:45:00 2001] [Author ID1: at Fri Aug 31 01:35:00 2001]transportador[Author ID1: at Fri Aug 31 01:45:00 2001] de 10.5 Kda q conecta el [Author ID1: at Fri Aug 31 01:35:00 2001]citocromo[Author ID1: at Fri Aug 31 01:36:00 2001] [Author ID1: at Fri Aug 31 01:35:00 2001]b ó f con el siguiente intermediario de la cadena transportadora q es el centro de [Author ID1: at Fri Aug 31 01:36:00 2001]reacción[Author ID1: at Fri Aug 31 01:45:00 2001] del PS I[Author ID1: at Fri Aug 31 01:36:00 2001] , P[Author ID1: at Fri Aug 31 01:37:00 2001]700[Author ID1: at Fri Aug 31 01:37:00 2001].[Author ID0: at ]

    En ocasiones se puede dar un [Author ID1: at Fri Aug 31 01:37:00 2001]-->transporte electrónico [Author ID1: at Fri Aug 31 01:37:00 2001][Author ID1: at Sun Sep 2 18:20:00 2001]-->cíclico[Author ID1: at Fri Aug 31 01:44:00 2001][Author ID1: at Sun Sep 2 18:20:00 2001] [Author ID1: at Fri Aug 31 01:37:00 2001]alrededor[Author ID1: at Fri Aug 31 01:38:00 2001] [Author ID1: at Fri Aug 31 01:37:00 2001]del PS I.[Author ID1: at Fri Aug 31 01:38:00 2001] (no se disocia [Author ID1: at Sun Sep 2 18:45:00 2001]ningún[Author ID1: at Sun Sep 2 18:46:00 2001] H[Author ID1: at Sun Sep 2 18:45:00 2001]2[Author ID1: at Sun Sep 2 18:45:00 2001]O [Author ID1: at Sun Sep 2 18:45:00 2001]porque[Author ID1: at Sun Sep 2 18:46:00 2001] no pa[Author ID1: at Sun Sep 2 18:45:00 2001]rticipa el PS II, de nodo q no hay formación de NADPH).[Author ID1: at Sun Sep 2 18:46:00 2001]-->[Author ID1: at Fri Aug 31 01:38:00 2001][Author ID1: at Sun Sep 2 18:45:00 2001]

    (Hoja 37 [Author ID1: at Fri Aug 31 01:38:00 2001]Fig.[Author ID1: at Fri Aug 31 01:44:00 2001] 8.25)[Author ID1: at Fri Aug 31 01:38:00 2001] Cuando los e[Author ID1: at Fri Aug 31 01:38:00 2001]-[Author ID1: at Fri Aug 31 01:38:00 2001] llegan a la ferredoxina van al [Author ID1: at Fri Aug 31 01:38:00 2001]citocromo[Author ID1: at Fri Aug 31 01:39:00 2001] [Author ID1: at Fri Aug 31 01:38:00 2001]b[Author ID1: at Fri Aug 31 01:39:00 2001]6[Author ID1: at Sun Sep 2 17:57:00 2001] f y de ahí al PS I. Este transporte contribuye a la creación del [Author ID1: at Fri Aug 31 01:39:00 2001]gradiente[Author ID1: at Fri Aug 31 01:44:00 2001] [Author ID1: at Fri Aug 31 01:39:00 2001]electroquímico[Author ID1: at Fri Aug 31 01:40:00 2001],[Author ID1: at Fri Aug 31 01:39:00 2001] pero no genera poder reductor en forma de NADPH. Esto es [Author ID1: at Fri Aug 31 01:40:00 2001]así[Author ID1: at Fri Aug 31 01:45:00 2001] porque a la vez q cede e[Author ID1: at Fri Aug 31 01:40:00 2001]-[Author ID1: at Fri Aug 31 01:40:00 2001], cede los H[Author ID1: at Fri Aug 31 01:40:00 2001]+[Author ID1: at Fri Aug 31 01:41:00 2001] al lumen.[Author ID0: at ]

    Hay acumulación de H[Author ID1: at Fri Aug 31 01:41:00 2001]+[Author ID1: at Fri Aug 31 01:41:00 2001] q favorecen la [Author ID1: at Fri Aug 31 01:41:00 2001]fotofosforilación[Author ID1: at Fri Aug 31 01:44:00 2001] cíclica.[Author ID0: at ]

    Esto va a ser importante en algunas plantas del grupo q tienen un metabolismo de tipo C[Author ID1: at Fri Aug 31 01:41:00 2001]4[Author ID1: at Fri Aug 31 01:42:00 2001]. [Author ID1: at Fri Aug 31 01:42:00 2001]

    Una vez q los e[Author ID1: at Fri Aug 31 01:43:00 2001]-[Author ID1: at Fri Aug 31 01:43:00 2001] llegan al P[Author ID1: at Fri Aug 31 01:43:00 2001]700[Author ID1: at Fri Aug 31 01:43:00 2001], toma [Author ID1: at Fri Aug 31 01:43:00 2001]energía[Author ID1: at Fri Aug 31 01:44:00 2001] para impulsar los e[Author ID1: at Fri Aug 31 01:43:00 2001]-[Author ID1: at Fri Aug 31 01:44:00 2001] en [Author ID1: at Fri Aug 31 01:43:00 2001]su transferencia al NADP[Author ID1: at Fri Aug 31 01:44:00 2001].[Author ID0: at ]

    El P[Author ID1: at Fri Aug 31 01:46:00 2001]700[Author ID1: at Fri Aug 31 01:46:00 2001] (PS I) esta incluido en un complejo multiproteico q consta del d[Author ID1: at Fri Aug 31 01:47:00 2001]í[Author ID1: at Fri Aug 31 02:06:00 2001]mero de P[Author ID1: at Fri Aug 31 01:47:00 2001]700[Author ID1: at Fri Aug 31 01:48:00 2001], unas 100 clorofila distintas del P[Author ID1: at Fri Aug 31 01:48:00 2001]700[Author ID1: at Fri Aug 31 01:48:00 2001], numerosas [Author ID1: at Fri Aug 31 01:48:00 2001]proteínas[Author ID1: at Fri Aug 31 02:06:00 2001] a las q se asocia el PS I, dos polipéptido de 66 y 70 Kda [Author ID1: at Fri Aug 31 01:48:00 2001]a la q [Author ID1: at Fri Aug 31 01:49:00 2001]se[Author ID1: at Fri Aug 31 02:06:00 2001] une la [Author ID1: at Fri Aug 31 01:49:00 2001]clorofila[Author ID1: at Fri Aug 31 02:06:00 2001] del P[Author ID1: at Fri Aug 31 01:49:00 2001]700[Author ID1: at Fri Aug 31 01:49:00 2001] y [Author ID1: at Fri Aug 31 01:49:00 2001]proteínas[Author ID1: at Fri Aug 31 02:06:00 2001] de Pm de 4-25 Kda.[Author ID0: at ]

    A estas [Author ID1: at Fri Aug 31 01:49:00 2001]proteínas[Author ID1: at Fri Aug 31 02:06:00 2001] se asocian de [Author ID1: at Fri Aug 31 01:49:00 2001]algún[Author ID1: at Fri Aug 31 02:06:00 2001] modo tanto la [Author ID1: at Fri Aug 31 01:49:00 2001]plastocianina[Author ID1: at Fri Aug 31 01:50:00 2001] [Author ID1: at Fri Aug 31 01:49:00 2001]y ferredoxina. [Author ID1: at Fri Aug 31 01:50:00 2001]Existe[Author ID1: at Fri Aug 31 02:06:00 2001] una [Author ID1: at Fri Aug 31 01:50:00 2001]proteína[Author ID1: at Fri Aug 31 02:06:00 2001] de 8 Kda a la q se unen [Author ID1: at Fri Aug 31 01:50:00 2001]proteínas[Author ID1: at Fri Aug 31 02:06:00 2001] sulfoferrosa[Author ID1: at Fri Aug 31 01:50:00 2001]s[Author ID1: at Fri Sep 7 21:00:00 2001] q [Author ID1: at Fri Aug 31 01:50:00 2001]intervienen[Author ID1: at Fri Aug 31 02:06:00 2001] [Author ID1: at Fri Aug 31 01:50:00 2001]en[Author ID1: at Fri Aug 31 02:05:00 2001] la [Author ID1: at Fri Aug 31 01:50:00 2001]trasferencia[Author ID1: at Fri Aug 31 02:05:00 2001] de e[Author ID1: at Fri Aug 31 01:50:00 2001]-[Author ID1: at Fri Aug 31 01:51:00 2001] del P[Author ID1: at Fri Aug 31 01:51:00 2001]700[Author ID1: at Fri Aug 31 01:51:00 2001] a la ferredoxina.[Author ID0: at ]

    Los aceptores primarios del P[Author ID1: at Fri Aug 31 01:51:00 2001]700[Author ID1: at Fri Aug 31 01:51:00 2001] tienen una fuerte tendencia a ceder e[Author ID1: at Fri Aug 31 01:51:00 2001]-[Author ID1: at Fri Aug 31 01:52:00 2001], tienen una vida corta y son difíciles de reconocer estos A[Author ID1: at Fri Aug 31 01:52:00 2001]0[Author ID1: at Fri Aug 31 01:54:00 2001] y A[Author ID1: at Fri Aug 31 01:54:00 2001]1[Author ID1: at Fri Aug 31 01:54:00 2001]. A[Author ID1: at Fri Aug 31 01:54:00 2001]0 [Author ID1: at Fri Aug 31 01:54:00 2001]puede q sea una molécula de clorofila a q [Author ID1: at Fri Aug 31 01:54:00 2001]absorbe[Author ID1: at Fri Aug 31 02:05:00 2001] a 430 nm denominado P[Author ID1: at Fri Aug 31 01:54:00 2001]430[Author ID1: at Fri Aug 31 01:55:00 2001] y el A[Author ID1: at Fri Aug 31 01:55:00 2001]1[Author ID1: at Fri Aug 31 01:55:00 2001] seria un quinona denominada fitoquinona.[Author ID0: at ]

    A[Author ID1: at Fri Aug 31 01:55:00 2001]0[Author ID1: at Fri Aug 31 01:55:00 2001] y[Author ID1: at Fri Aug 31 01:55:00 2001] [Author ID1: at Fri Aug 31 02:05:00 2001]A[Author ID1: at Fri Aug 31 01:55:00 2001]1[Author ID1: at Fri Aug 31 01:56:00 2001] cuando [Author ID1: at Fri Aug 31 01:56:00 2001]están[Author ID1: at Fri Aug 31 02:05:00 2001] reducidos son agentes reductores muy potentes con un vida media corta.[Author ID0: at ]

    Hay tres complejos sulfoferrosos: FeS[Author ID1: at Fri Aug 31 01:56:00 2001]x[Author ID1: at Fri Aug 31 01:57:00 2001], FeS[Author ID1: at Fri Aug 31 01:57:00 2001]a[Author ID1: at Fri Aug 31 01:57:00 2001] y FeS[Author ID1: at Fri Aug 31 01:57:00 2001]b[Author ID1: at Fri Aug 31 01:57:00 2001]. A [Author ID1: at Fri Aug 31 01:57:00 2001]través[Author ID1: at Fri Aug 31 02:05:00 2001] de estos los e[Author ID1: at Fri Aug 31 01:57:00 2001]-[Author ID1: at Fri Aug 31 01:57:00 2001] pasan a la ferredoxina q participa en procesos de [Author ID1: at Fri Aug 31 01:57:00 2001]asimilación[Author ID1: at Fri Aug 31 01:58:00 2001] [Author ID1: at Fri Aug 31 01:57:00 2001]de N[Author ID1: at Fri Aug 31 01:58:00 2001]2[Author ID1: at Fri Aug 31 01:58:00 2001] [Author ID1: at Fri Aug 31 01:58:00 2001]atmosférico[Author ID1: at Fri Aug 31 02:05:00 2001], cede los e[Author ID1: at Fri Aug 31 01:58:00 2001]-[Author ID1: at Fri Aug 31 01:58:00 2001] a la nitrogenasa en la [Author ID1: at Fri Aug 31 01:58:00 2001]fijación[Author ID1: at Fri Aug 31 01:59:00 2001] [Author ID1: at Fri Aug 31 01:58:00 2001]de N[Author ID1: at Fri Aug 31 01:59:00 2001]2[Author ID1: at Fri Aug 31 01:59:00 2001] y reducción de SO[Author ID1: at Fri Aug 31 01:59:00 2001]4[Author ID1: at Fri Aug 31 01:59:00 2001]=[Author ID1: at Fri Aug 31 01:59:00 2001] a sulfuro.[Author ID0: at ]

    Los e[Author ID1: at Fri Aug 31 01:59:00 2001]-[Author ID1: at Fri Aug 31 02:00:00 2001] q llegan a la ferredoxina pasan al NADP mediante una flavoprote[Author ID1: at Fri Aug 31 02:00:00 2001]í[Author ID1: at Fri Aug 31 02:04:00 2001]na soluble con Pm 40 Kda.[Author ID0: at ]

    De este modo se termina la CTE [Author ID1: at Fri Aug 31 02:00:00 2001]acumulándose[Author ID1: at Fri Aug 31 02:01:00 2001] [Author ID1: at Fri Aug 31 02:00:00 2001]la [Author ID1: at Fri Aug 31 02:01:00 2001]energía[Author ID1: at Fri Aug 31 02:04:00 2001] en equivalentes r[Author ID1: at Fri Aug 31 02:01:00 2001]e[Author ID1: at Fri Aug 31 02:04:00 2001]dox.[Author ID0: at ]

    Los e[Author ID1: at Fri Aug 31 02:01:00 2001]-[Author ID1: at Fri Aug 31 02:01:00 2001] en vez de acabar en NADP si este no esta oxidado[Author ID1: at Fri Aug 31 02:01:00 2001],[Author ID1: at Fri Aug 31 02:03:00 2001] viajan [Author ID1: at Fri Aug 31 02:01:00 2001]alrededor[Author ID1: at Fri Aug 31 02:02:00 2001] [Author ID1: at Fri Aug 31 02:01:00 2001]del PS I por un transporte electroquímico [Author ID1: at Fri Aug 31 02:02:00 2001]cíclico al citocromo b[Author ID1: at Fri Aug 31 02:03:00 2001]6[Author ID1: at Sun Sep 2 18:53:00 2001]f q a [Author ID1: at Fri Aug 31 02:03:00 2001]través[Author ID1: at Fri Aug 31 02:06:00 2001] de la plastocianina llegan al P[Author ID1: at Fri Aug 31 02:03:00 2001]700[Author ID1: at Fri Aug 31 02:04:00 2001]. cada vez q los e[Author ID1: at Fri Aug 31 02:04:00 2001]-[Author ID1: at Fri Aug 31 02:04:00 2001] pasan[Author ID1: at Fri Aug 31 02:07:00 2001] al citocromo b ó f se incorporan H[Author ID1: at Fri Aug 31 02:08:00 2001]+[Author ID1: at Fri Aug 31 02:08:00 2001] en el interior del lumen.[Author ID0: at ]

    Los H[Author ID1: at Fri Aug 31 02:08:00 2001]+[Author ID1: at Fri Aug 31 02:08:00 2001] [Author ID1: at Fri Aug 31 02:08:00 2001]darán[Author ID1: at Fri Aug 31 02:18:00 2001] origen al gradiente [Author ID1: at Fri Aug 31 02:08:00 2001]electroquímico[Author ID1: at Fri Aug 31 02:09:00 2001] [Author ID1: at Fri Aug 31 02:08:00 2001]q [Author ID1: at Fri Aug 31 02:09:00 2001]dará[Author ID1: at Fri Aug 31 02:18:00 2001] lugar a la síntesis de ATP.[Author ID1: at Fri Aug 31 02:09:00 2001]

    -->(Hoja 38 [Author ID1: at Fri Aug 31 02:09:00 2001][Author ID1: at Fri Aug 31 02:18:00 2001]-->Fig.[Author ID1: at Fri Aug 31 02:18:00 2001][Author ID1: at Fri Aug 31 02:18:00 2001]--> 8.34)[Author ID1: at Fri Aug 31 02:09:00 2001][Author ID1: at Fri Aug 31 02:18:00 2001] El transporte de e[Author ID1: at Fri Aug 31 02:09:00 2001]-[Author ID1: at Fri Aug 31 02:10:00 2001] puede estar bloqueado por agentes químicos usados como [Author ID1: at Fri Aug 31 02:10:00 2001]herbicidas[Author ID1: at Fri Aug 31 02:18:00 2001]. Algunos herbicidas impiden la CTE. Unos lo inhiben a nivel de la zona reductora del PS I y el otro grupo lo p[Author ID1: at Fri Aug 31 02:10:00 2001]aran a nivel de quinonas el transporte de e[Author ID1: at Fri Aug 31 02:11:00 2001]-[Author ID1: at Fri Aug 31 02:11:00 2001] . DCMU.[Author ID1: at Fri Aug 31 02:11:00 2001]

    -->A los primeros corresponde el paraquat[Author ID1: at Fri Aug 31 02:12:00 2001][Author ID1: at Fri Aug 31 02:21:00 2001]. [Author ID1: at Fri Aug 31 02:12:00 2001]Captan los e[Author ID1: at Fri Aug 31 02:13:00 2001]-[Author ID1: at Fri Aug 31 02:13:00 2001] [Author ID1: at Sun Sep 2 18:48:00 2001]de la quinona, se reduce no cede los electrones. Cuando se reduce cede los e[Author ID1: at Fri Aug 31 02:13:00 2001]-[Author ID1: at Fri Aug 31 02:14:00 2001] al O[Author ID1: at Fri Aug 31 02:14:00 2001]2[Author ID1: at Fri Aug 31 02:14:00 2001] y forma el radical [Author ID1: at Fri Aug 31 02:14:00 2001]superóxido[Author ID1: at Fri Aug 31 02:18:00 2001] atacando a los lípidos de membrana y [Author ID1: at Fri Aug 31 02:14:00 2001]destruyéndolas[Author ID1: at Fri Aug 31 02:15:00 2001].[Author ID1: at Fri Aug 31 02:14:00 2001][Author ID0: at ]

    El radical superóxido puede combinarse con H[Author ID1: at Fri Aug 31 02:15:00 2001]+[Author ID1: at Fri Aug 31 02:15:00 2001] dando H[Author ID1: at Fri Aug 31 02:15:00 2001]2[Author ID1: at Fri Aug 31 02:15:00 2001]O[Author ID1: at Fri Aug 31 02:15:00 2001]2[Author ID1: at Fri Aug 31 02:15:00 2001] q también es perjudicial.[Author ID0: at ]

    En [Author ID1: at Fri Aug 31 02:15:00 2001]los cloroplastos esta la catalasa q degrada el H[Author ID1: at Fri Aug 31 02:16:00 2001]2[Author ID1: at Fri Aug 31 02:16:00 2001]O[Author ID1: at Fri Aug 31 02:16:00 2001]2[Author ID1: at Fri Aug 31 02:16:00 2001] liberando O[Author ID1: at Fri Aug 31 02:16:00 2001]2[Author ID1: at Fri Aug 31 02:16:00 2001] y agua. También esta la ascorbato peroxidasa q destruye el H[Author ID1: at Fri Aug 31 02:16:00 2001]2[Author ID1: at Fri Aug 31 02:17:00 2001]O[Author ID1: at Fri Aug 31 02:17:00 2001]2[Author ID1: at Fri Aug 31 02:17:00 2001] con el ascórbico, para dar dos de [Author ID1: at Fri Aug 31 02:17:00 2001]H[Author ID1: at Sun Sep 2 18:56:00 2001]2[Author ID1: at Sun Sep 2 18:57:00 2001]O[Author ID1: at Sun Sep 2 18:57:00 2001]. [Author ID1: at Fri Aug 31 02:17:00 2001][Author ID1: at Fri Aug 31 02:18:00 2001]

    --> [Author ID1: at Tue Aug 28 18:53:00 2001][Author ID1: at Fri Aug 31 02:17:00 2001]-->Al otro grupo pertenece el DCMU[Author ID1: at Tue Aug 28 18:53:00 2001][Author ID1: at Fri Aug 31 02:21:00 2001]-->.[Author ID1: at Tue Aug 28 18:53:00 2001][Author ID1: at Fri Aug 31 02:17:00 2001] Este se [Author ID1: at Fri Aug 31 02:19:00 2001]sitúa[Author ID1: at Fri Aug 31 02:20:00 2001] en la [Author ID1: at Fri Aug 31 02:19:00 2001]proteína[Author ID1: at Fri Aug 31 02:20:00 2001] de 32 Kda a la q se une la quinona. El DCMU no toma los e[Author ID1: at Fri Aug 31 02:19:00 2001]-[Author ID1: at Fri Aug 31 02:20:00 2001], pero impide q la quinona los tome impidiendo el transporte de H[Author ID1: at Fri Aug 31 02:20:00 2001]+[Author ID1: at Fri Aug 31 02:20:00 2001].[Author ID1: at Fri Aug 31 02:20:00 2001] [Author ID1: at Tue Aug 28 18:53:00 2001][Author ID0: at ]

    La mutación de un aa en la [Author ID1: at Fri Aug 31 02:21:00 2001]proteína[Author ID1: at Fri Aug 31 02:23:00 2001] de 32 KDA[Author ID1: at Fri Aug 31 02:21:00 2001] (se pasa de Gly a Cis) da resistencia a este herbicida.[Author ID0: at ]

    [Author ID1: at Fri Aug 31 02:22:00 2001]

    Conversión de la energía en ATP. Fotofosforilación (Hoja 39 Fig. 8.37)[Author ID1: at Fri Aug 31 02:23:00 2001] [Author ID1: at Tue Aug 28 18:53:00 2001][Author ID0: at ]

    La [Author ID1: at Fri Aug 31 02:24:00 2001]energía[Author ID1: at Fri Aug 31 02:28:00 2001] se puede utilizar para la síntesis de ATP.[Author ID0: at ]

    En el transcurso de la transferencia de e[Author ID1: at Fri Aug 31 02:24:00 2001]-[Author ID1: at Fri Aug 31 02:24:00 2001] estamos creando una carga de H[Author ID1: at Fri Aug 31 02:24:00 2001]+[Author ID1: at Fri Aug 31 02:25:00 2001] en el lumen.[Author ID0: at ]

    En principio, para q se de el acumulo de H[Author ID1: at Fri Aug 31 02:25:00 2001]+[Author ID1: at Fri Aug 31 02:25:00 2001] tiene q darse un transporte de e[Author ID1: at Fri Aug 31 02:25:00 2001]-[Author ID1: at Fri Aug 31 02:25:00 2001].[Author ID0: at ]

    Existen agentes desacoplantes q descargan el lumen de H[Author ID1: at Fri Aug 31 02:25:00 2001]+[Author ID1: at Fri Aug 31 02:26:00 2001] dándose solo el transporte y no la síntesis de ATP. Uno puede ser el propio amonio[Author ID1: at Fri Aug 31 02:26:00 2001] (NH[Author ID1: at Sun Sep 2 20:50:00 2001]4[Author ID1: at Sun Sep 2 20:50:00 2001])[Author ID1: at Sun Sep 2 20:50:00 2001]. Otros pueden ser varinomicima, nigericina, gramicidina, dinitrofenol[Author ID1: at Fri Aug 31 02:26:00 2001].[Author ID1: at Fri Aug 31 02:28:00 2001] [Author ID1: at Tue Aug 28 18:53:00 2001][Author ID0: at ]

    [Author ID0: at ]

    El [Author ID1: at Fri Aug 31 02:28:00 2001]-->mecanismo de [Author ID1: at Fri Aug 31 02:28:00 2001][Author ID1: at Fri Aug 31 16:40:00 2001]-->formación[Author ID1: at Fri Aug 31 02:30:00 2001][Author ID1: at Fri Aug 31 16:40:00 2001]--> de [Author ID1: at Fri Aug 31 02:28:00 2001][Author ID1: at Fri Aug 31 16:40:00 2001]-->ATP[Author ID1: at Fri Aug 31 02:30:00 2001][Author ID1: at Fri Aug 31 16:40:00 2001] [Author ID1: at Fri Aug 31 02:28:00 2001]es a [Author ID1: at Fri Aug 31 02:29:00 2001]través[Author ID1: at Fri Aug 31 02:30:00 2001] de la [Author ID1: at Fri Aug 31 02:29:00 2001]teoría[Author ID1: at Fri Aug 31 02:31:00 2001] quimiosm[Author ID1: at Fri Aug 31 02:29:00 2001]ó[Author ID1: at Fri Aug 31 02:31:00 2001]tica [Author ID1: at Fri Aug 31 02:29:00 2001]propuesta[Author ID1: at Fri Aug 31 02:31:00 2001] por Michel, valida también para la síntesis de[Author ID1: at Fri Aug 31 02:29:00 2001] [Author ID1: at Fri Aug 31 02:31:00 2001]ATP por las bacterias y p[Author ID1: at Fri Aug 31 02:29:00 2001]o[Author ID1: at Fri Aug 31 02:31:00 2001]r el q se sintetiza ATP en las mitocondrias como el q se da en los cloroplastos.[Author ID1: at Fri Aug 31 02:29:00 2001][Author ID0: at ]

    Paralelo al transporte de e[Author ID1: at Fri Aug 31 11:48:00 2001]-[Author ID1: at Fri Aug 31 11:55:00 2001] se produce una [Author ID1: at Fri Aug 31 11:48:00 2001]acumulación[Author ID1: at Fri Aug 31 11:49:00 2001] [Author ID1: at Fri Aug 31 11:48:00 2001]de H[Author ID1: at Fri Aug 31 11:49:00 2001]+[Author ID1: at Fri Aug 31 11:55:00 2001] entre los dos lados de una membrana (mitocondrial, Tilacoide, bacteroide).[Author ID0: at ]

    El [Author ID1: at Fri Aug 31 11:49:00 2001]principio [Author ID1: at Fri Aug 31 11:50:00 2001]básico[Author ID1: at Fri Aug 31 11:54:00 2001] de quimiosmosiss indica q la distribución asimétrica de H[Author ID1: at Fri Aug 31 11:50:00 2001]+[Author ID1: at Fri Aug 31 11:55:00 2001] es la fuerza q se utiliza para la [Author ID1: at Fri Aug 31 11:50:00 2001]síntesis[Author ID1: at Fri Aug 31 11:51:00 2001] [Author ID1: at Fri Aug 31 11:50:00 2001]de ATP a partir de ADP+P[Author ID1: at Fri Aug 31 11:51:00 2001]i[Author ID1: at Fri Aug 31 11:51:00 2001]. También se establece una diferencia de carga entre los dos lados de la membrana [Author ID1: at Fri Aug 31 11:51:00 2001]además[Author ID1: at Fri Aug 31 11:54:00 2001] del gradiente [Author ID1: at Fri Aug 31 11:51:00 2001]químico[Author ID1: at Fri Aug 31 11:52:00 2001].[Author ID1: at Fri Aug 31 11:51:00 2001] Esta [Author ID1: at Fri Aug 31 11:52:00 2001]diferencia[Author ID1: at Fri Aug 31 11:54:00 2001] electroquímica es la fuente de [Author ID1: at Fri Aug 31 11:52:00 2001]energía[Author ID1: at Fri Aug 31 11:54:00 2001] par[Author ID1: at Fri Aug 31 11:52:00 2001]a[Author ID1: at Mon Sep 3 16:04:00 2001] q se de la síntesis de ATP.[Author ID1: at Fri Aug 31 11:52:00 2001] [Author ID1: at Tue Aug 28 18:53:00 2001][Author ID1: at Fri Aug 31 13:37:00 2001]

    -->([Author ID1: at Fri Aug 31 13:37:00 2001][Author ID1: at Fri Aug 31 13:38:00 2001]-->Fig.[Author ID1: at Fri Aug 31 13:38:00 2001][Author ID1: at Fri Aug 31 13:38:00 2001]--> 8.36)[Author ID1: at Fri Aug 31 13:37:00 2001][Author ID1: at Fri Aug 31 13:38:00 2001]--> [Author ID1: at Tue Aug 28 18:53:00 2001][Author ID1: at Fri Aug 31 13:38:00 2001]-->Factor de acoplamiento de [Author ID1: at Tue Aug 28 18:53:00 2001][Author ID1: at Fri Aug 31 13:38:00 2001]la [Author ID1: at Fri Aug 31 13:38:00 2001]-->ATP[Author ID1: at Fri Aug 31 13:38:00 2001][Author ID1: at Fri Aug 31 16:42:00 2001]-->asa[Author ID1: at Fri Aug 31 13:38:00 2001][Author ID1: at Fri Aug 31 16:42:00 2001]--> [Author ID1: at Fri Aug 31 13:59:00 2001][Author ID1: at Fri Aug 31 16:42:00 2001]se da la síntesis de ATP a partir de ADP+P[Author ID1: at Fri Aug 31 13:59:00 2001]i[Author ID1: at Fri Aug 31 14:00:00 2001]. Este complejo con un [Author ID1: at Fri Aug 31 14:31:00 2001]Pm[Author ID1: at Fri Aug 31 14:32:00 2001] 400 Kda tiene dos componentes: [Author ID1: at Fri Aug 31 14:31:00 2001]-->una [Author ID1: at Fri Aug 31 14:31:00 2001][Author ID1: at Fri Aug 31 16:42:00 2001]-->porción[Author ID1: at Fri Aug 31 14:32:00 2001][Author ID1: at Fri Aug 31 16:42:00 2001]--> [Author ID1: at Fri Aug 31 14:31:00 2001][Author ID1: at Fri Aug 31 16:42:00 2001]-->hidrófoba[Author ID1: at Fri Aug 31 14:32:00 2001][Author ID1: at Fri Aug 31 16:42:00 2001] inmersa en la membrana tilacoidal q representa el canal por donde salen H[Author ID1: at Fri Aug 31 14:31:00 2001]+[Author ID1: at Fri Aug 31 14:32:00 2001]--> [Author ID1: at Tue Aug 28 18:53:00 2001][Author ID1: at Fri Aug 31 13:38:00 2001]y [Author ID1: at Fri Aug 31 14:33:00 2001]-->otra hidrófila[Author ID1: at Fri Aug 31 14:33:00 2001][Author ID1: at Fri Aug 31 16:42:00 2001] hacia el exterior del estroma donde esta el centro activo y donde se une[Author ID1: at Fri Aug 31 14:33:00 2001]n[Author ID1: at Fri Aug 31 14:34:00 2001] el ADP y el P[Author ID1: at Fri Aug 31 14:33:00 2001]i[Author ID1: at Fri Aug 31 14:34:00 2001] para la síntesis [Author ID1: at Fri Aug 31 14:34:00 2001]--> de ATP.[Author ID1: at Tue Aug 28 18:53:00 2001][Author ID1: at Fri Aug 31 13:38:00 2001] L[Author ID1: at Fri Aug 31 14:34:00 2001]a [Author ID1: at Fri Aug 31 14:35:00 2001]energía[Author ID1: at Fri Aug 31 14:37:00 2001] necesaria para la síntesis de ATP tiene dos componentes: uno [Author ID1: at Fri Aug 31 14:35:00 2001]químico[Author ID1: at Fri Aug 31 14:36:00 2001] [Author ID1: at Fri Aug 31 14:35:00 2001]q es un componente electroquímico de H[Author ID1: at Fri Aug 31 14:36:00 2001]+[Author ID1: at Fri Aug 31 14:36:00 2001] debido a la variación de pH y otro [Author ID1: at Fri Aug 31 14:36:00 2001]eléctrico[Author ID1: at Fri Aug 31 14:37:00 2001] transmembranal.[Author ID1: at Fri Aug 31 14:36:00 2001]--> [Author ID1: at Tue Aug 28 18:53:00 2001][Author ID1: at Fri Aug 31 13:38:00 2001][Author ID0: at ]

    En la síntesis de ATP de cloroplastos es [Author ID1: at Fri Aug 31 14:38:00 2001]más[Author ID1: at Mon Sep 3 15:37:00 2001] [Author ID1: at Fri Aug 31 14:38:00 2001]importante[Author ID1: at Fri Aug 31 14:42:00 2001] el gradiente de pH, en mitocondrias es [Author ID1: at Fri Aug 31 14:38:00 2001]más[Author ID1: at Mon Sep 3 15:37:00 2001] importante el gradiente [Author ID1: at Fri Aug 31 14:38:00 2001]eléctrico[Author ID1: at Fri Aug 31 14:42:00 2001].[Author ID1: at Fri Aug 31 14:38:00 2001][Author ID0: at ]

    Cada 4 H[Author ID1: at Fri Aug 31 14:39:00 2001]+[Author ID1: at Fri Aug 31 14:39:00 2001] q salen de la ATP[Author ID1: at Fri Aug 31 14:39:00 2001]asa[Author ID1: at Fri Aug 31 14:40:00 2001] se produce la síntesis de un ATP.[Author ID0: at ]

    La ATP[Author ID1: at Fri Aug 31 14:40:00 2001]asa[Author ID1: at Fri Aug 31 14:40:00 2001] se localiza en los tilacoides estromales.[Author ID0: at ]

    Los H[Author ID1: at Fri Aug 31 14:40:00 2001]+[Author ID1: at Fri Aug 31 14:40:00 2001] tienen q viajar por el lumen hasta llegar al estroma para fo[Author ID1: at Fri Aug 31 14:40:00 2001]rmar el ATP.[Author ID1: at Fri Aug 31 14:41:00 2001][Author ID0: at ]

    [Author ID0: at ]

    [Author ID1: at Fri Aug 31 14:41:00 2001]

    -->Tema 8[Author ID1: at Fri Aug 31 14:41:00 2001][Author ID1: at Fri Aug 31 14:44:00 2001]--> [Author ID1: at Fri Aug 31 14:42:00 2001][Author ID1: at Fri Aug 31 14:44:00 2001]-->fijación[Author ID1: at Fri Aug 31 14:43:00 2001][Author ID1: at Fri Aug 31 14:44:00 2001]--> del [Author ID1: at Fri Aug 31 14:42:00 2001][Author ID1: at Fri Aug 31 14:44:00 2001]-->anhídrido[Author ID1: at Fri Aug 31 14:43:00 2001][Author ID1: at Fri Aug 31 14:44:00 2001]--> [Author ID1: at Fri Aug 31 14:42:00 2001][Author ID1: at Fri Aug 31 14:44:00 2001]-->carbónico[Author ID1: at Fri Aug 31 14:43:00 2001][Author ID1: at Fri Aug 31 14:44:00 2001] CO[Author ID1: at Fri Aug 31 16:36:00 2001]2[Author ID1: at Fri Aug 31 16:36:00 2001]-->[Author ID1: at Fri Aug 31 14:43:00 2001][Author ID1: at Fri Aug 31 16:36:00 2001]

    [Author ID1: at Fri Aug 31 14:44:00 2001]

    -->[Author ID1: at Fri Aug 31 14:43:00 2001][Author ID1: at Fri Aug 31 14:44:00 2001]

    En el sentido estricto, el [Author ID1: at Fri Aug 31 14:44:00 2001]único[Author ID1: at Fri Aug 31 14:48:00 2001] proceso [Author ID1: at Fri Aug 31 14:44:00 2001]luminoso[Author ID1: at Fri Aug 31 14:48:00 2001] es la [Author ID1: at Fri Aug 31 14:44:00 2001]captación[Author ID1: at Fri Aug 31 14:45:00 2001] [Author ID1: at Fri Aug 31 14:44:00 2001]de la radiación.[Author ID0: at ]

    La utilización del NADPH y el ATP para la reducción del CO[Author ID1: at Fri Aug 31 14:45:00 2001]2[Author ID1: at Fri Aug 31 14:45:00 2001] a CH q requiere un gasto de 3 ATP se ha denominado [Author ID1: at Fri Aug 31 14:46:00 2001]fase oscura[Author ID1: at Fri Aug 31 14:46:00 2001] porque se puede dar en el laboratorio, si se le añade el ATP. [Author ID1: at Fri Aug 31 14:46:00 2001]Lo q ocurre es q muchas enzimas de Calvin se activa[Author ID1: at Fri Aug 31 14:47:00 2001]n[Author ID1: at Mon Sep 3 13:34:00 2001] cuando son [Author ID1: at Fri Aug 31 14:47:00 2001]iluminados[Author ID1: at Fri Aug 31 14:48:00 2001] los cloroplastos[Author ID1: at Fri Aug 31 14:47:00 2001] [Author ID1: at Fri Aug 31 14:48:00 2001]por eso no se puede decir q la fase oscura sea [Author ID1: at Fri Aug 31 14:49:00 2001]independiente[Author ID1: at Fri Aug 31 14:53:00 2001] de la luz.[Author ID1: at Fri Aug 31 14:49:00 2001] Las enzimas[Author ID1: at Mon Sep 3 13:40:00 2001] [Author ID1: at Mon Sep 3 13:42:00 2001]activadas tienen grupos disulfuro q se reducen a dos grupos [Author ID1: at Mon Sep 3 13:40:00 2001]sulfhidrilo cuando son activados por la luz blanca.[Author ID1: at Mon Sep 3 13:41:00 2001][Author ID1: at Fri Aug 31 14:49:00 2001]

    [Author ID1: at Fri Aug 31 14:50:00 2001]

    [Author ID1: at Mon Sep 3 11:27:00 2001]

    Hay tres etapas:[Author ID0: at ]

    [Author ID0: at ]

    Salvo [Author ID1: at Fri Aug 31 16:25:00 2001]algún[Author ID1: at Fri Aug 31 16:29:00 2001] tipo de bacterias fotosintéticas todos los organismos vegetales tienen la 2ª y 3ª etapa.[Author ID1: at Fri Aug 31 16:25:00 2001]

    Las diferencias [Author ID1: at Fri Aug 31 16:26:00 2001]están[Author ID1: at Fri Aug 31 16:29:00 2001] en el modo de la fijación del CO[Author ID1: at Fri Aug 31 16:26:00 2001]2[Author ID1: at Fri Aug 31 16:26:00 2001]:[Author ID1: at Fri Aug 31 16:26:00 2001]

    La [Author ID1: at Fri Aug 31 16:30:00 2001]fase oscura se da en el estroma con el CO[Author ID1: at Fri Aug 31 16:31:00 2001]2[Author ID1: at Fri Aug 31 16:32:00 2001] [Author ID1: at Fri Aug 31 16:32:00 2001]atmosférico[Author ID1: at Fri Aug 31 16:36:00 2001], ATP y NADH. Se requiere luz para activar enzimas para q se de todo el proceso de fijación.[Author ID1: at Fri Aug 31 16:32:00 2001][Author ID0: at ]

    Según como se de la entrada de CO[Author ID1: at Fri Aug 31 16:44:00 2001]2[Author ID1: at Fri Aug 31 16:45:00 2001] por la hoja hasta el lugar de carboxilación da lugar a [Author ID1: at Fri Aug 31 16:45:00 2001]-->tres tipos de fotosíntesis[Author ID1: at Fri Aug 31 16:45:00 2001][Author ID1: at Fri Aug 31 16:46:00 2001]:[Author ID1: at Fri Aug 31 16:45:00 2001][Author ID1: at Fri Aug 31 16:46:00 2001]

  • -->Ciclo de Calvin[Author ID1: at Fri Aug 31 16:46:00 2001][Author ID1: at Mon Sep 3 11:38:00 2001] o ciclo reductor de pentosas P o C. [Author ID1: at Fri Aug 31 16:46:00 2001]-->C[Author ID1: at Fri Aug 31 16:47:00 2001][Author ID1: at Mon Sep 3 11:38:00 2001]-->3[Author ID1: at Fri Aug 31 16:47:00 2001][Author ID1: at Mon Sep 3 11:38:00 2001] [Author ID1: at Fri Aug 31 16:47:00 2001]porque[Author ID1: at Fri Aug 31 16:50:00 2001] el primer producto de la carboxilación son dos moléculas de 3PGA.[Author ID1: at Fri Aug 31 16:47:00 2001][Author ID1: at Fri Aug 31 17:06:00 2001]

  • [Author ID1: at Fri Aug 31 16:48:00 2001]

    RuBP + CO[Author ID1: at Fri Aug 31 16:48:00 2001]2[Author ID1: at Fri Aug 31 16:48:00 2001] [Author ID1: at Fri Aug 31 16:48:00 2001] 2 (3 PGA)[Author ID1: at Fri Aug 31 16:52:00 2001][Author ID1: at Fri Aug 31 17:06:00 2001]

    [Author ID1: at Fri Aug 31 16:56:00 2001]

  • -->M[Author ID1: at Fri Aug 31 17:01:00 2001][Author ID1: at Mon Sep 3 11:38:00 2001]-->etabolismo[Author ID1: at Fri Aug 31 16:58:00 2001][Author ID1: at Mon Sep 3 11:38:00 2001]--> C[Author ID1: at Fri Aug 31 16:56:00 2001][Author ID1: at Mon Sep 3 11:38:00 2001]-->4[Author ID1: at Fri Aug 31 16:57:00 2001][Author ID1: at Mon Sep 3 11:38:00 2001]: se obtienen [Author ID1: at Fri Aug 31 16:57:00 2001]ácidos[Author ID1: at Fri Aug 31 16:58:00 2001] dicarbox[Author ID1: at Fri Aug 31 16:57:00 2001]í[Author ID1: at Fri Aug 31 16:58:00 2001]licos de 4 [Author ID1: at Fri Aug 31 16:57:00 2001]átomos[Author ID1: at Fri Aug 31 16:58:00 2001] de carbono. El C se va a fijar sobre el PEP y el C se fija en forma de bicarbonato.[Author ID1: at Fri Aug 31 16:57:00 2001] Hay una separación espacial entre la fijación y reducción de CO[Author ID1: at Fri Aug 31 17:03:00 2001]2[Author ID1: at Fri Aug 31 17:03:00 2001].[Author ID1: at Fri Aug 31 17:06:00 2001]

  • [Author ID1: at Fri Aug 31 16:57:00 2001]

    PEP + [Author ID1: at Fri Aug 31 16:59:00 2001]-->HCO[Author ID1: at Fri Aug 31 16:59:00 2001][Author ID1: at Fri Aug 31 16:59:00 2001]3 [Author ID1: at Fri Aug 31 16:59:00 2001]-[Author ID1: at Fri Aug 31 16:59:00 2001] [Author ID1: at Fri Aug 31 17:00:00 2001] OAA Malato[Author ID1: at Fri Aug 31 17:00:00 2001][Author ID1: at Fri Aug 31 17:06:00 2001]

    [Author ID1: at Fri Aug 31 17:00:00 2001]

  • -->CAM, metabolismo [Author ID1: at Fri Aug 31 17:01:00 2001][Author ID1: at Mon Sep 3 11:38:00 2001]-->ácido[Author ID1: at Fri Aug 31 17:07:00 2001][Author ID1: at Mon Sep 3 11:38:00 2001]--> de las crasulaceas[Author ID1: at Fri Aug 31 17:01:00 2001][Author ID1: at Mon Sep 3 11:38:00 2001]: el C se fija sobre el PEP en forma de bicarbonato para dar OAA y luego se reduce a mala[Author ID1: at Fri Aug 31 17:01:00 2001]to. Hay una separación temporal entre la fijación y la [Author ID1: at Fri Aug 31 17:04:00 2001]reducción[Author ID1: at Fri Aug 31 17:05:00 2001] [Author ID1: at Fri Aug 31 17:04:00 2001]del CO[Author ID1: at Fri Aug 31 17:05:00 2001]2[Author ID1: at Fri Aug 31 17:05:00 2001], por la noche fijan el CO[Author ID1: at Fri Aug 31 17:05:00 2001]2[Author ID1: at Fri Aug 31 17:05:00 2001] y el malato es acumulado en la vacuola y durante el [Author ID1: at Fri Aug 31 17:05:00 2001]día[Author ID1: at Fri Aug 31 17:08:00 2001] se da la refijaci[Author ID1: at Fri Aug 31 17:05:00 2001]ó[Author ID1: at Fri Aug 31 17:07:00 2001]n del CO[Author ID1: at Fri Aug 31 17:05:00 2001]2[Author ID1: at Fri Aug 31 17:06:00 2001].[Author ID1: at Fri Aug 31 17:06:00 2001][Author ID1: at Fri Aug 31 17:07:00 2001]

  • -->[Author ID1: at Fri Aug 31 16:54:00 2001][Author ID1: at Fri Aug 31 17:06:00 2001]

    [Author ID1: at Fri Aug 31 17:07:00 2001]PEP + HCO[Author ID1: at Fri Aug 31 17:06:00 2001]3 [Author ID1: at Fri Aug 31 17:06:00 2001]- [Author ID1: at Fri Aug 31 17:06:00 2001] OAA Malato[Author ID1: at Fri Aug 31 17:06:00 2001][Author ID0: at ]

    [Author ID1: at Fri Aug 31 17:08:00 2001]

    -->[Author ID1: at Fri Aug 31 14:53:00 2001][Author ID1: at Fri Aug 31 16:45:00 2001]

    Ciclo de Calvin[Author ID1: at Fri Aug 31 17:21:00 2001]

    1ª etapa[Author ID1: at Fri Aug 31 17:22:00 2001] carboxilación[Author ID1: at Fri Aug 31 17:35:00 2001]:[Author ID1: at Fri Aug 31 17:22:00 2001] [Author ID1: at Fri Aug 31 17:22:00 2001]-->(Hoja 44 [Author ID1: at Fri Aug 31 17:23:00 2001][Author ID1: at Fri Aug 31 17:24:00 2001]-->Fig.[Author ID1: at Fri Aug 31 17:24:00 2001][Author ID1: at Fri Aug 31 17:24:00 2001]--> 9.3)[Author ID1: at Fri Aug 31 17:23:00 2001][Author ID1: at Fri Aug 31 17:24:00 2001] [Author ID1: at Fri Aug 31 17:24:00 2001]el CO[Author ID1: at Fri Aug 31 17:22:00 2001]2 [Author ID1: at Fri Aug 31 17:22:00 2001]se fija sobre la RuBP por la [Author ID1: at Fri Aug 31 17:22:00 2001]RUBISCO[Author ID1: at Fri Aug 31 17:23:00 2001] [Author ID1: at Fri Aug 31 17:22:00 2001]formándose un intermediario [Author ID1: at Fri Aug 31 17:23:00 2001]inestable[Author ID1: at Fri Aug 31 17:24:00 2001] para dar 2 [Author ID1: at Fri Aug 31 17:23:00 2001]moléculas[Author ID1: at Fri Aug 31 17:24:00 2001] de 3 PGA[Author ID1: at Fri Aug 31 17:23:00 2001].[Author ID1: at Fri Aug 31 17:24:00 2001]-->[Author ID1: at Fri Aug 31 14:53:00 2001][Author ID1: at Fri Aug 31 17:22:00 2001]

    2ª etapa[Author ID1: at Fri Aug 31 17:25:00 2001] reducción[Author ID1: at Fri Aug 31 17:35:00 2001]-->:[Author ID1: at Fri Aug 31 17:25:00 2001][Author ID1: at Fri Aug 31 17:26:00 2001]--> (Hoja 45)[Author ID1: at Fri Aug 31 17:25:00 2001][Author ID1: at Fri Aug 31 17:26:00 2001] etapa reductora. En [Author ID1: at Fri Aug 31 17:26:00 2001]una 1ª etapa se fosforila gastándose las 2/3 partes del ATP y se reduce gastándose todo el poder reductor por la 3PGA deshidrogenasa NADP dependiente.[Author ID1: at Fri Aug 31 17:27:00 2001][Author ID1: at Fri Aug 31 17:34:00 2001]

    [Author ID1: at Fri Aug 31 17:37:00 2001]De las 6 [Author ID1: at Fri Aug 31 17:29:00 2001]moléculas[Author ID1: at Fri Aug 31 17:35:00 2001] de G3P solo una triosa-P se considera como producto del ciclo donde se utiliza para la [Author ID1: at Fri Aug 31 17:29:00 2001]síntesis[Author ID1: at Fri Aug 31 17:30:00 2001] [Author ID1: at Fri Aug 31 17:29:00 2001]de sacarosa. El resto, mediante 10 reacciones regeneran las 3 [Author ID1: at Fri Aug 31 17:30:00 2001]moléculas[Author ID1: at Fri Aug 31 17:36:00 2001] de 5C sobre las q el C se fija.[Author ID1: at Fri Aug 31 17:30:00 2001]-->[Author ID1: at Fri Aug 31 14:52:00 2001][Author ID1: at Fri Aug 31 17:29:00 2001]

    3ª etapa regeneración:[Author ID1: at Fri Aug 31 17:37:00 2001] [Author ID1: at Fri Aug 31 17:38:00 2001] una vez generado el G3P hay q regenerar la RuBP, por medio de una [Author ID1: at Fri Aug 31 17:38:00 2001]isomerización[Author ID1: at Fri Aug 31 17:43:00 2001].[Author ID1: at Fri Aug 31 17:38:00 2001]

    Se condensan 2 [Author ID1: at Fri Aug 31 17:40:00 2001]moléculas[Author ID1: at Fri Aug 31 17:43:00 2001] de G3P y DHAP por una aldolasa para dar Fructosa 1,6[Author ID1: at Fri Aug 31 17:40:00 2001]-[Author ID1: at Mon Sep 3 12:10:00 2001]BP[Author ID1: at Fri Aug 31 17:40:00 2001],[Author ID1: at Fri Aug 31 17:41:00 2001] q es hidrolizada [Author ID1: at Mon Sep 3 12:03:00 2001]mediante[Author ID1: at Mon Sep 3 12:10:00 2001] una fosfatasa [Author ID1: at Mon Sep 3 12:03:00 2001]liberando[Author ID1: at Mon Sep 3 12:10:00 2001] un P dando Fructosa[Author ID1: at Mon Sep 3 12:03:00 2001]-[Author ID1: at Mon Sep 3 12:10:00 2001]6P[Author ID1: at Mon Sep 3 12:03:00 2001]. Este P se tiene q [Author ID1: at Mon Sep 3 12:04:00 2001]liberar[Author ID1: at Mon Sep 3 12:10:00 2001] para q el ciclo luminoso pueda mantenerse.[Author ID0: at ]

    Por [Author ID1: at Mon Sep 3 12:04:00 2001]una transcetolasa se da la transferencia del carbono C[Author ID1: at Mon Sep 3 12:05:00 2001]1 [Author ID1: at Mon Sep 3 12:05:00 2001]y [Author ID1: at Mon Sep 3 12:05:00 2001]C[Author ID1: at Mon Sep 3 12:06:00 2001]2[Author ID1: at Mon Sep 3 12:06:00 2001] de la Fructosa 6P sobre otra molécula de G3P.[Author ID0: at ]

    A continuación una segunda [Author ID1: at Mon Sep 3 12:06:00 2001]aldolasa[Author ID1: at Mon Sep 3 12:07:00 2001] [Author ID1: at Mon Sep 3 12:06:00 2001]condensa el [Author ID1: at Mon Sep 3 12:07:00 2001]Eritrosa-[Author ID1: at Mon Sep 3 12:09:00 2001]4P con una DHAP para dar una molécula de 7C, la Sedoheptulosa 1,7-BP.[Author ID1: at Mon Sep 3 12:07:00 2001] Por los siguientes paso[Author ID1: at Fri Aug 31 17:41:00 2001]s[Author ID1: at Mon Sep 3 12:09:00 2001] se [Author ID1: at Fri Aug 31 17:41:00 2001]llega[Author ID1: at Fri Aug 31 17:43:00 2001] una ribulosa en forma ceto, q [Author ID1: at Fri Aug 31 17:41:00 2001]habrá[Author ID1: at Fri Aug 31 17:43:00 2001] q fosforilar mediante la Ribulosa 5-Pkinasa.[Author ID1: at Fri Aug 31 17:41:00 2001][Author ID1: at Fri Aug 31 17:42:00 2001]

    [Author ID1: at Mon Sep 3 12:36:00 2001]

    [Author ID1: at Mon Sep 3 12:30:00 2001]

    -->6CO[Author ID1: at Mon Sep 3 12:30:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001]-->2[Author ID1: at Mon Sep 3 12:30:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001] [Author ID1: at Mon Sep 3 12:35:00 2001]-->+[Author ID1: at Mon Sep 3 12:30:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001] [Author ID1: at Mon Sep 3 12:35:00 2001]-->18ATP[Author ID1: at Mon Sep 3 12:30:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001] [Author ID1: at Mon Sep 3 12:35:00 2001]-->+[Author ID1: at Mon Sep 3 12:30:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001] [Author ID1: at Mon Sep 3 12:35:00 2001]-->12(NA[Author ID1: at Mon Sep 3 12:30:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001]-->DPH+H[Author ID1: at Mon Sep 3 12:31:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001]-->+[Author ID1: at Mon Sep 3 12:31:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001]-->)[Author ID1: at Mon Sep 3 12:31:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001] [Author ID1: at Mon Sep 3 12:36:00 2001]-->>>>>>>>[Author ID1: at Mon Sep 3 12:31:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001] [Author ID1: at Mon Sep 3 12:36:00 2001]-->Hexosa[Author ID1: at Mon Sep 3 12:31:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001] [Author ID1: at Mon Sep 3 12:36:00 2001]-->P[Author ID1: at Mon Sep 3 12:31:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001] [Author ID1: at Mon Sep 3 12:35:00 2001]-->+[Author ID1: at Mon Sep 3 12:31:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001] [Author ID1: at Mon Sep 3 12:35:00 2001]-->18ADP[Author ID1: at Mon Sep 3 12:31:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001] [Author ID1: at Mon Sep 3 12:35:00 2001]-->+[Author ID1: at Mon Sep 3 12:31:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001] [Author ID1: at Mon Sep 3 12:35:00 2001]-->P[Author ID1: at Mon Sep 3 12:31:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001]-->i[Author ID1: at Mon Sep 3 12:32:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001] [Author ID1: at Mon Sep 3 12:35:00 2001]-->+[Author ID1: at Mon Sep 3 12:32:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001] [Author ID1: at Mon Sep 3 12:35:00 2001]-->12NADP[Author ID1: at Mon Sep 3 12:32:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001]-->+[Author ID1: at Mon Sep 3 12:32:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001] [Author ID1: at Mon Sep 3 12:35:00 2001]-->+[Author ID1: at Mon Sep 3 12:34:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001] [Author ID1: at Mon Sep 3 12:35:00 2001]-->H[Author ID1: at Mon Sep 3 12:32:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001]-->+[Author ID1: at Mon Sep 3 12:32:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001]-->[Author ID1: at Mon Sep 3 12:20:00 2001][Author ID1: at Mon Sep 3 12:35:00 2001]

    [Author ID1: at Mon Sep 3 12:36:00 2001]

    Enzimas q actúan en el ciclo.[Author ID1: at Mon Sep 3 12:13:00 2001][Author ID1: at Mon Sep 3 12:14:00 2001]

    Rubisco (irreversible), 3-fosfoglicerato qu[Author ID1: at Mon Sep 3 12:14:00 2001]inasa, Gliceraldehido 3p-deshidro[Author ID1: at Mon Sep 3 12:15:00 2001]genasa[Author ID1: at Mon Sep 3 12:20:00 2001], Trio[Author ID1: at Mon Sep 3 12:15:00 2001]sa P isomerasa, Aldolasa, Fructosa 1,6-BP fosfatasa (irreversible), Transcetolasa, Sedoheptulosa 1,7-BP [Author ID1: at Mon Sep 3 12:16:00 2001]fosfatasa (irreversible), Transcetolasa, Ribulosa 5P e[Author ID1: at Mon Sep 3 12:17:00 2001]pimerasa, Ribulosa 5P isomerasa, Ribulosa 5P kinasa (irreversible).[Author ID1: at Mon Sep 3 12:18:00 2001]-->[Author ID1: at Fri Aug 31 17:42:00 2001][Author ID1: at Mon Sep 3 12:14:00 2001]

    [Author ID1: at Mon Sep 3 12:20:00 2001]

    Capacidad autocatalítica del ciclo.[Author ID1: at Fri Aug 31 17:43:00 2001][Author ID1: at Fri Aug 31 17:44:00 2001]

    Las 5/6 partes de las triosas sirven par[Author ID1: at Fri Aug 31 17:44:00 2001]a[Author ID1: at Mon Sep 3 16:04:00 2001] regenerar el aceptor, solo 1/6 parte se usa para la [Author ID1: at Fri Aug 31 17:44:00 2001]síntesis[Author ID1: at Fri Aug 31 17:45:00 2001] [Author ID1: at Fri Aug 31 17:44:00 2001]de sacarosa o almidón en los cloroplastos.[Author ID1: at Fri Aug 31 17:45:00 2001][Author ID0: at ]

    [Author ID1: at Fri Aug 31 21:23:00 2001]

    [Author ID0: at ]

    [Author ID1: at Mon Sep 3 12:36:00 2001]

    Eficiencia [Author ID1: at Fri Aug 31 21:23:00 2001]termodinámica[Author ID1: at Fri Aug 31 21:24:00 2001]

    La mayor perdida [Author ID1: at Fri Aug 31 21:24:00 2001]energética[Author ID1: at Fri Aug 31 21:28:00 2001] se produce en el proceso de formación del ATP y del NADPH[Author ID1: at Fri Aug 31 21:24:00 2001] durante las [Author ID1: at Fri Aug 31 21:28:00 2001]reacción[Author ID1: at Fri Aug 31 21:29:00 2001] luminosas y no tanto en la fase oscur[Author ID1: at Fri Aug 31 21:28:00 2001]a ([Author ID1: at Fri Aug 31 21:29:00 2001]-->Ciclo[Author ID1: at Fri Aug 31 21:29:00 2001][Author ID1: at Mon Sep 3 12:38:00 2001] de Calvin).[Author ID1: at Fri Aug 31 21:29:00 2001]

    La elevada eficacia de la fase oscura implica q las reaccione[Author ID1: at Fri Aug 31 21:30:00 2001]s[Author ID1: at Mon Sep 3 12:37:00 2001] del Ciclo de [Author ID1: at Fri Aug 31 21:30:00 2001]Calvin[Author ID1: at Fri Aug 31 21:31:00 2001] [Author ID1: at Fri Aug 31 21:30:00 2001]tengan q estar [Author ID1: at Fri Aug 31 21:31:00 2001]bien[Author ID1: at Fri Aug 31 21:35:00 2001] reguladas para mantener este elevado rendimiento. El control de [Author ID1: at Fri Aug 31 21:31:00 2001]todo[Author ID1: at Fri Aug 31 21:35:00 2001] el proceso se lleva a cabo a dos niveles:[Author ID1: at Fri Aug 31 21:31:00 2001]