BIOLOGÍA

FOTOSINTESIS

UNIVERSIDAD PERUANA CAYETANO HEREDIACENTRO FORMATIVO PREUNIVERSITARIO

FOTOSINTESISDEFINICIÓN

Transformación de la energía luminosa en energía química

En todas las plantas verdes, las cianofíceas y algunas bacterias

Sintetizan glúcidos o hidratos de carbono

Leaf cross sectionVein

Mesophyll

Stomata CO2 O2

Mesophyll cellChloroplast

5 µm

Outermembrane

Intermembranespace

Innermembrane

Thylakoidspace

ThylakoidGranumStroma

1 µm

Reactants:

Products:

6 CO2 12 H2O

C6H12O6 6 H2O 6 O2

FOTOSINTESISLUZ

•Más larga la longitud de onda de la luz visible más rojo es el color. •Longitudes de onda corta están en la zona violeta del espectro. •Las longitudes de onda más largas que las del rojo se denominan infrarrojas, y más cortas que el violeta, ultravioleta

LE 10-6

Visible light

Gammarays X-rays UV Infrared Micro-

wavesRadiowaves

10–5 nm 10–3 nm 1 nm 103 nm 106 nm1 m

(109 nm) 103 m

380 450 500 550 600 650 700 750 nm

Longer wavelengthLower energy

Shorter wavelengthHigher energy

Chloroplast

LightReflected light

Absorbed light

Transmitted light

Granum

Whitelight

Refractingprism

Chlorophyllsolution

Photoelectrictube

Galvanometer

The high transmittance (low absorption) reading indicates that chlorophyll absorbs very little green light.

Greenlight

Slit moves to pass light of selected wavelength

0 100

Whitelight

Refractingprism

Chlorophyllsolution

Photoelectrictube

The low transmittance (high absorption) reading indicates that chlorophyll absorbs most blue light.

Bluelight

Slit moves to pass light of selected wavelength

0 100

Chlorophyll a

Chlorophyll b

Carotenoids

Wavelength of light (nm)Absorption spectra

Abs

orpt

ion

of li

ght b

ych

loro

plas

t pig

men

ts

400 500 600 700

CH3

CHO

in chlorophyll ain chlorophyll b

Porphyrin ring:light-absorbing“head” of molecule; note magnesium atom at center

Hydrocarbon tail:interacts with hydrophobicregions of proteins insidethylakoid membranes of chloroplasts; H atoms not shown

FOTOSINTESISPigmentos Accesorios

•Carotenoides (amarillo, rojo, púrpura).

•Beta caroteno es precurso de la Vitamina A (rojo).

•Xantofila es un carotenoide amarillo

FOTOSINTESISEtapas de Fotosíntesis

FOTOSINTESISFase Luminosa

•Depende Directamente de la Luz

•Ocurre en la membrana del Tilacoide

•Fotopigmentos organizados en fotosistemas (200 moléculas de clorofila y 50 de carotenoides)•Fotosistema I, con centro de reacción de clorofila a, pico de absorción en 700nm (P700).

•Fotosistema II, pico de absorción a 680nm (P680nm)

Excitedstate

Heat

Photon(fluorescence)

GroundstateChlorophyll

molecule

Photon

Excitation of isolated chlorophyll molecule

Ener

gy o

f ele

ctro

n

e–

Thylakoid

Photon

Light-harvestingcomplexes

Photosystem

Reactioncenter

STROMA

Primary electronacceptor

e–

Transferof energy

Specialchlorophyll amolecules

Pigmentmolecules

THYLAKOID SPACE(INTERIOR OF THYLAKOID)

Thyl

akoi

d m

embr

ane

H2O

LIGHTREACTIONS

Chloroplast

Light

H2O

LIGHTREACTIONS

Chloroplast

Light

ATP

NADPH

O2

H2O

LIGHTREACTIONS

Chloroplast

Light

ATP

NADPH

O2

NADP+

CO2

ADPP+ i CALVIN

CYCLE

[CH2O](sugar)

LightP680

e–

Photosystem II(PS II)

Primaryacceptor

[CH2O] (sugar)

NADPH

ATP

ADP

CALVINCYCLELIGHT

REACTIONS

NADP+

Light

H2O CO2

Ener

gy o

f ele

ctro

nsO2

LightP680

e–

Photosystem II(PS II)

Primaryacceptor

[CH2O] (sugar)

NADPH

ATP

ADP

CALVINCYCLELIGHT

REACTIONS

NADP+

Light

H2O CO2

Ener

gy o

f ele

ctro

nsO2

e–

e–

+2 H+

H2O

O21/2

LightP680

e–

Photosystem II(PS II)

Primaryacceptor

[CH2O] (sugar)

NADPH

ATP

ADP

CALVINCYCLELIGHT

REACTIONS

NADP+

Light

H2O CO2

Ener

gy o

f ele

ctro

nsO2

e–

e–

+2 H+

H2O

O21/2

Pq

Cytochromecomplex

Electron transport chain

Pc

ATP

LightP680

e–

Photosystem II(PS II)

Primaryacceptor

[CH2O] (sugar)

NADPH

ATP

ADP

CALVINCYCLELIGHT

REACTIONS

NADP+

Light

H2O CO2

Ener

gy o

f ele

ctro

ns

O2

e–

e–

+2 H+

H2O

O21/2

Pq

Cytochromecomplex

Electron transport chain

Pc

ATP

P700

e–

Primaryacceptor

Photosystem I(PS I)

Light

LightP680

e–

Photosystem II(PS II)

Primaryacceptor

[CH2O] (sugar)

NADPH

ATP

ADPCALVINCYCLELIGHT

REACTIONS

NADP+

Light

H2O CO2En

ergy

of e

lect

rons

O2

e–

e–

+2 H+

H2O

O21/2

Pq

Cytochromecomplex

Electron transport chain

Pc

ATP

P700

e–

Primaryacceptor

Photosystem I(PS I)

e–e–

ElectronTransportchain

NADP+

reductase

Fd

NADP+

NADPH+ H+

+ 2 H+

Light

Photosystem IPhotosystem II ATP

Pc

Fd

Cytochromecomplex

Pq

Primaryacceptor

Fd

NADP+

reductase

NADP+

NADPH

Primaryacceptor

LE 10-16

MITOCHONDRIONSTRUCTURE

Intermembranespace

MembraneElectrontransport

chain

Mitochondrion Chloroplast

CHLOROPLASTSTRUCTURE

Thylakoidspace

Stroma

ATP

Matrix

ATPsynthase

Key

H+ Diffusion

ADP + PH+

i

Higher [H+]Lower [H+]

STROMA(Low H+ concentration)

Light

Photosystem II Cytochromecomplex

2 H+

LightPhotosystem I

NADP+

reductaseFd

PcPq

H2O O2

+2 H+

1/22 H+

NADP+ + 2H+

+ H+NADPH

ToCalvincycle

THYLAKOID SPACE(High H+ concentration)

STROMA(Low H+ concentration)

Thylakoidmembrane ATP

synthase

ATPADP

+P

H+i

[CH2O] (sugar)O2

NADPH

ATP

ADPNADP+

CO2H2O

LIGHTREACTIONS

CALVINCYCLE

Light

[CH2O] (sugar)O2

NADPH

ATP

ADPNADP+

CO2H2O

LIGHTREACTIONS

CALVINCYCLE

LightInput

3CO2

(Entering oneat a time)

Rubisco

3 P PShort-lived

intermediate

Phase 1: Carbon fixation

6 P3-Phosphoglycerate

6 ATP

6 ADP

CALVINCYCLE

3 P PRibulose bisphosphate

(RuBP)

[CH2O] (sugar)O2

NADPH

ATP

ADPNADP+

CO2H2O

LIGHTREACTIONS

CALVINCYCLE

Light Input

CO2

(Entering oneat a time)

Rubisco

3 P PShort-lived

intermediate

Phase 1: Carbon fixation

6 P3-Phosphoglycerate

6 ATP

6 ADP

CALVINCYCLE

3

P PRibulose bisphosphate

(RuBP)

3

6 NADP+

6

6 NADPH

P i

6 P1,3-Bisphosphoglycerate

P

6 PGlyceraldehyde-3-phosphate

(G3P)

P1G3P

(a sugar)Output

Phase 2:Reduction

Glucose andother organiccompounds

[CH2O] (sugar)O2

NADPH

ATP

ADPNADP+

CO2H2O

LIGHTREACTIONS

CALVINCYCLE

Light Input

CO2

(Entering oneat a time)

Rubisco

3 P PShort-lived

intermediate

Phase 1: Carbon fixation

6 P3-Phosphoglycerate

6 ATP

6 ADP

CALVINCYCLE

3

P PRibulose bisphosphate

(RuBP)

3

6 NADP+

6

6 NADPH

P i

6 P1,3-Bisphosphoglycerate

P

6 PGlyceraldehyde-3-phosphate

(G3P)

P1G3P

(a sugar)Output

Phase 2:Reduction

Glucose andother organiccompounds

3

3 ADP

ATP

Phase 3:Regeneration ofthe CO2 acceptor(RuBP) P5

G3P

LE 10-21

Light

CO2H2O

Light reactions Calvin cycle

NADP+

RuBP

G3PATP

Photosystem IIElectron transport

chainPhotosystem I

O2

Chloroplast

NADPH

ADP+ P i

3-Phosphoglycerate

Starch(storage)

Amino acidsFatty acids

Sucrose (export)