fotosíntesis` final2009
TRANSCRIPT
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Bio 111
2009
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• Luz se transforma en energía química(compuesto orgánico)
• Ocurre en el cloroplasto
• Requiere pigmentos fotosintéticos
• Plantas, algas, bacterias fotosintéticas
• CO2 se convierte en carbohidrato
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luz
6 CO2 + 12H2O ---> C6H12O6 +6O2 +6H2O
clorofila
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Figure 7-1 Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc.
photosynthesis
cellularrespiration
(mitochondrion)
O2ATP sugar CO2H2O
(chloroplast)
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Luz◦Compuesta de fotones
Luz visible es una porciónpequeña del espectroelectromagnético◦ La energía viaja en ondas◦Onda corta más energía que ondalarga
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Fotosíntesis es un procesoredox◦ Se captura la energía solar y se transforma en carbohidrato◦Hidrógenos del agua reducen el carbono◦Oxígeno del agua se oxida
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TV andradiowaves
Micro-waves
Infrared
Visible
UV
X-rays
Gammarays
Colorspectrumof visiblelight
Red
Orange
Yellow
Green
Blue
Violet
760 nm
700 nm
600 nm
500 nm
400 nm
380 nm
One wavelength
Longer wavelength
Electromagneticspectrum Shorter wavelength
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100µm
(a)
Wavelength of light (nm)
(b)
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Cloroplastos◦Organelos rodeados de doblemembrana◦ Lugar de fotosíntesis◦ Localizados principalmente en el mesófilo de la hoja
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Palisademesophyll
Vein
Spongy mesophyll
Stoma(a)
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Figure 7-2d Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc.
Chloroplast
channelinterconnectingthylakoids
stroma
thylakoid
outer membrane
inner membrane
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10µm(b)
Thylakoids Outer membrane
Innermembrane
Intermembranespace
Thylakoidmembrane
Stroma Granum(stack ofthylakoids)
Thylakoidlumen(c)
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Clorofila◦ Pigmento fotosintético -principal◦Clorofila a, clorofila b, carotenoides, se encuentran en las membranastilacoides de los cloroplastos
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Fotosistemas I y II◦Dos tipos de unidades fotosintéticas◦Cada fotosistema incluye Moléculas de clorofila Complejos de antenas
◦ Centro de reacción del Fotosistema I P700 pico de absorción en 700 nm
◦ Centro de reacción Fotosistema II P680 pico de reabsorción en 680 nm
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Primaryelectronacceptor
Photon
Photosystem
Chloroplast
Thylakoid
Antennacomplexes
Reactioncenter
e–
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Esti
mat
ed a
bso
rpti
on
(%
)
Wavelength (nm)
Chlorophyll b
Chlorophyll a(a)
Rel
ativ
e ra
te o
f p
ho
tosy
nth
esis
Wavelength (nm)
(b)
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Figure 7-5 Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc.
chlorophyll b
Wavelength (nanometers)
Micro-
wavesGamma rays X-rays UV Infrared
Radio
waves
Visible light
higher energy(too much)
lower energy(not enough)
light absorp
tion
(perc
ent)
Absorbance of photosynthetic pigments
chlorophyll a
carotenoids
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Fases de fotosíntesis◦Dependiente de luz tilacoides Los electrones energizados por la luz se
convierten en ATP
◦ Fijación de carbono estroma Compuestos productos de la fase
dependiente se requieren para la formación de carbohidrato
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Figure 7-4 Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc.
CO2
LIGHT-DEPENDENTREACTIONS(in thylakoids)
LIGHT-INDEPENDENTREACTIONS(in stroma)
DEPLETEDCARRIERS
(ADP, NADP+)
ENERGIZEDCARRIERS
(ATP, NADPH)
H2O
glucose
O2
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Figure 7-11 Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc.
O2
energy fromsunlight
chloroplast
Light-independentreactions(C3 cycle) occurin stroma.
Light-dependentreactions areassociated withthylakoids.
CO2
NADP+
sugar
NADPH
ADP
ATP
H2O
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La luz es absorbida por la clorofila
Clorofila excitada-nivel energético alto
Libera electrones altos en energía, se ioniza, queda con carga positiva-Fotoionización
Electrones pasan cadena transporte
Se degradan energéticamente cíclica
no cíclica
La clorofila se neutraliza
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Transporte de electronescíclica◦ Electrones del fotosistema I regresanal fotosistema I◦ Se genera ATP por quimiosmosis◦No NADPH, no O2
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Light-dependent reactions Carbon fixation reactions
ATP
ADP
NADPH
NADP+
Lightreactions
Calvincycle
H2O O2CO2
Carbohydrates
Chloroplast
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Light-dependent reactions(in thylakoids)
Carbon fixation reactions(in stroma)
ATP
ADP
NADPH
NADP+
Lightreactions
Calvincycle
H2O O2CO2
Carbohydrates
Chloroplast
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Transporte de electrones no cíclica◦ Se forma ATP y NADPH◦ Electrones energizados por luz son aceptados por NADP+
◦Una serie de reacciones redox◦ Electrones que provienen de P680 son reemplazados por los queprovienen del H2O◦Ocurre fotolisis
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H2O -- ½ O2 + 2H+ 2e_
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Oxi
dat
ion
-re
du
ctio
n p
ote
nti
al (
volt
s) (
rela
tive
en
ergy
leve
l)
Primaryelectronacceptor
Primaryelectronacceptor
NADPHNADP+
H2O
ATP
O2
ADP
1
2
Photosystem II(P680)
Productionof ATP bychemiosmosis
H+
Ferredoxin
Plastiquinone
Cytochromecomplex
Plastocyanin
1/2 + 2 H+
Pi
A0
A1
FeSx
FeSB
FeSA
Photosystem I(P700)
(from medium)
Electrontransportchain
Electrontransportchain
2e-
2 e
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Figure 7-8 (part 2) Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc.
C3
cycle
PSII PSIETC
stroma
ETC
thylakoid space
Energy fromenergizedelectrons powersNADPH synthesis.
Flow of H+ downconcentration gradientpowers ATP synthesis.
Energy from energizedelectrons powers activetransport of H+ by ETC.
High H+ concentrationgenerated by activetransport.
H+ channel coupledto ATP-synthesizingenzyme.
Energy-carriermolecules powerthe C3 cycle.
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Síntesis de ATP y transporte de electrones◦ Electrones se mueven en cadena de electrones◦ Protones (H+) se mueven de la estroma hacia el lumen del tilacoide, creando un gradiente de protones
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Figure E7-2 (part 2) Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc.
stroma
thylakoidmembrane
photosystem II
2e–
ATPADP
P
Active transport
of hydrogen ions.
High H+ concentration
in thylakoid space.
H+ ion channel coupled
to ATP synthesizing
enzyme.
Flow of H+ powers
ATP synthesis.
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ATP se utilizan en estroma
NADPH se utiliza en estroma
O2 se libera al aire
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Stroma
Thylakoid lumen
Thylakoid membrane Photons (H+)
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Light-dependent reactions Carbon fixation reactions
ATP
ADP
NADPH
NADP+
Lightreactions
Calvincycle
H2O O2CO2
Carbohydrates
Chloroplast
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Fijación del Carbono◦ Se forma carbohidrato a partir de CO2 , ATP, y NADPH
12 NADPH + 18 ATP + 6 CO2 →
C6H12O6 + 12 NADP + + 18 ADP + 18 Pi + 6 H2O
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Fases del ciclo de Calvin
◦ capturar CO2
◦ reducción del carbono
◦ regeneración de RuBP
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Figure 7-12a Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc.
CO2
C3 plants use the C3 pathway
bundle-sheathcells
In a C3 plant, mesophyll cellscontain chloroplasts; bundle-sheath cells do not.
Much photorespirationoccurs under hot, dryconditions.
Little glucoseis synthesized.
rubisco
G3P
CO2
PGA
O2
RuBP
glucose
within mesophyll chloropaststoma
C3
Cycle
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CO 2 molecules arecaptured by RuBP,resulting in an unstableintermediate that isimmediately brokenapart into 2 PGA
PGA is phosphorylatedby ATP and reduced byNADPH. Removal of aphosphate results information of G3P.
Through a series ofreactions G3P isrearranged into newRuBP molecules oranother sugar
Glucose and othercarbohydrate synthesis
2 moleculesof glyceraldehyde-3-phosphate (G3P)
6 molecules ofribulose bisphosphate(RuBP)
CALVINCYCLE
Carbonreductionphase
RuBPregenerationphase
CO2 uptakephase
12 NADPH
12 ADP
12 molecules ofphosphoglycerate(PGA)
12 ATP
6 molecules of CO2
10 moleculesof G3P
6 molecules of ribulosephosphate (RP)
ATP
6 ADP
P
P
P
P
P
P P
P
12 moleculesof glyceraldehyde-3-phosphate (G3P)
1
32
12 NADP+
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