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Chapter 10 Photosynthesis
Chapter 10 Photosynthesis
LE 10-2
Plants
Unicellular protist
Multicellular algae Cyanobacteria
Purple sulfurbacteria
10 µm
1.5 µm
40 µm
LE 10-3
Leaf cross sectionVein
Mesophyll
Stomata CO2O2
Mesophyll cellChloroplast
5 µm
Outermembrane
Intermembranespace
Innermembrane
Thylakoidspace
Thylakoid
GranumStroma
1 µm
LE 10-4
Reactants:
Products:
6 CO2 12 H2O
C6H12O6 6 H2O 6 O2
LE 10-5_1
H2O
LIGHTREACTIONS
Chloroplast
Light
LE 10-5_2
H2O
LIGHTREACTIONS
Chloroplast
Light
ATP
NADPH
O2
LE 10-5_3
H2O
LIGHTREACTIONS
Chloroplast
Light
ATP
NADPH
O2
NADP+
CO2
ADPP+ i
CALVINCYCLE
[CH2O](sugar)
LE 10-7
Chloroplast
Light
Reflected light
Absorbed light
Transmitted light
Granum
LE 10-8a
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
LE 10-8b
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
LE 10-9a
Chlorophyll a
Chlorophyll b
Carotenoids
Wavelength of light (nm)
Absorption spectra
Ab
sorp
tio
n o
f lig
ht
by
chlo
rop
last
pig
men
ts
400 500 600 700
LE 10-10
CH3
CHO
in chlorophyll a
in 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
LE 10-11
Excitedstate
Heat
Photon(fluorescence)
GroundstateChlorophyll
molecule
Photon
Excitation of isolated chlorophyll molecule Fluorescence
En
erg
y o
f el
ectr
on
e–
LE 10-12
Thylakoid
Photon
Light-harvestingcomplexes
Photosystem
Reactioncenter
STROMA
Primary electronacceptor
e–
Transferof energy
Specialchlorophyll amolecules
Pigmentmolecules
THYLAKOID SPACE(INTERIOR OF THYLAKOID)
Th
ylak
oid
mem
bra
ne
LE 10-13_1
LightP680
e–
Photosystem II(PS II)
Primaryacceptor
[CH2O] (sugar)
NADPH
ATP
ADP
CALVINCYCLE
LIGHTREACTIONS
NADP+
Light
H2O CO2
En
erg
y o
f el
ectr
on
sO2
LE 10-13_2
LightP680
e–
Photosystem II(PS II)
Primaryacceptor
[CH2O] (sugar)
NADPH
ATP
ADP
CALVINCYCLE
LIGHTREACTIONS
NADP+
Light
H2O CO2
En
erg
y o
f el
ectr
on
sO2
e–
e–
+2 H+
H2O
O21/2
LE 10-13_3
LightP680
e–
Photosystem II(PS II)
Primaryacceptor
[CH2O] (sugar)
NADPH
ATP
ADP
CALVINCYCLE
LIGHTREACTIONS
NADP+
Light
H2O CO2
En
erg
y o
f el
ectr
on
sO2
e–
e–
+2 H+
H2O
O21/2
Pq
Cytochromecomplex
Electron transport chain
Pc
ATP
LE 10-13_4
LightP680
e–
Photosystem II(PS II)
Primaryacceptor
[CH2O] (sugar)
NADPH
ATP
ADP
CALVINCYCLE
LIGHTREACTIONS
NADP+
Light
H2O CO2
En
erg
y o
f el
ectr
on
s
O2
e–
e–
+2 H+
H2O
O21/2
Pq
Cytochromecomplex
Electron transport chain
Pc
ATP
P700
e–
Primaryacceptor
Photosystem I(PS I)
Light
LE 10-13_5
LightP680
e–
Photosystem II(PS II)
Primaryacceptor
[CH2O] (sugar)
NADPH
ATP
ADPCALVINCYCLE
LIGHTREACTIONS
NADP+
Light
H2O CO2E
ner
gy
of
elec
tro
ns
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
LE 10-16
MITOCHONDRIONSTRUCTURE
Intermembranespace
MembraneElectrontransport
chain
Mitochondrion Chloroplast
CHLOROPLASTSTRUCTURE
Thylakoidspace
Stroma
ATP
Matrix
ATPsynthase
Key
H+ Diffusion
ADP + P
H+
i
Higher [H+]
Lower [H+]
LE 10-17
STROMA(Low H+ concentration)
Light
Photosystem IICytochrome
complex
2 H+
Light
Photosystem I
NADP+
reductase
Fd
PcPq
H2O O2
+2 H+
1/2
2 H+
NADP+ + 2H+
+ H+NADPH
ToCalvincycle
THYLAKOID SPACE(High H+ concentration)
STROMA(Low H+ concentration)
Thylakoidmembrane ATP
synthase
ATP
ADP+P
H+i
[CH2O] (sugar)O2
NADPH
ATP
ADP
NADP+
CO2H2O
LIGHTREACTIONS
CALVINCYCLE
Light
LE 10-18_1
[CH2O] (sugar)O2
NADPH
ATP
ADP
NADP+
CO2H2O
LIGHTREACTIONS
CALVINCYCLE
LightInput
3
CO2
(Entering oneat a time)
Rubisco
3 P P
Short-livedintermediate
Phase 1: Carbon fixation
6 P
3-Phosphoglycerate6 ATP
6 ADP
CALVINCYCLE
3 P P
Ribulose bisphosphate(RuBP)
RuBisCo
• Enzyme which fixes carbon from air– ribulose bisphosphate carboxylase – the most important enzyme in the world!
• it makes life out of air!
– definitely the most abundant enzyme
I’m green with envy!
It’s not easy being green!
LE 10-18_3
[CH2O] (sugar)O2
NADPH
ATP
ADP
NADP+
CO2H2O
LIGHTREACTIONS
CALVINCYCLE
Light Input
CO2
(Entering oneat a time)
Rubisco
3 P P
Short-livedintermediate
Phase 1: Carbon fixation
6 P
3-Phosphoglycerate6 ATP
6 ADP
CALVINCYCLE
3
P P
Ribulose bisphosphate(RuBP)
3
6 NADP+
6
6 NADPH
P i
6 P
1,3-BisphosphoglycerateP
6 P
Glyceraldehyde-3-phosphate(G3P)
P1
G3P(a sugar)Output
Phase 2:Reduction
Glucose andother organiccompounds
3
3 ADP
ATP
Phase 3:Regeneration ofthe CO2 acceptor(RuBP) P5
G3P
Adaptations to hot, dry climates:• Needles, waxy coatings, not losing leaves in winter, no leaves
• CAM – close stomates during day
- cacti, jade, pineapple
C4 –plants in hot regions with intense sunlight – sugarcane, corn. Leaves are modified so p.s. occurs in 2 different types of cells.
LE 10-20
Bundle-sheathcell
Mesophyllcell Organic acid
C4
CO2
CO2
CALVINCYCLE
Sugarcane Pineapple
Organic acidsrelease CO2 toCalvin cycle
CO2 incorporatedinto four-carbonorganic acids(carbon fixation)
Organic acid
CAM
CO2
CO2
CALVINCYCLE
Sugar
Spatial separation of steps Temporal separation of steps
Sugar
Day
Night
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)
Photosynthesis summary
1.Where did the energy come from?
2.Where did the electrons come from?
3.Where did the H2O come from?
4.Where did the O2 come from?
5.Where did the O2 go?
6.Where did the H+ come from?
7.Where did the ATP come from?
8.What will the ATP be used for?
9.Where did the NADPH come from?
10.What will the NADPH be used for?
