Photosynthesis Ch 7. Autotrophs Chloroplasts Contain chlorophyll – Green Site of photosynthesis...
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Transcript of Photosynthesis Ch 7. Autotrophs Chloroplasts Contain chlorophyll – Green Site of photosynthesis...
Photosynthesis
Ch 7
Autotrophs
Chloroplasts
• Contain chlorophyll– Green
• Site of photosynthesis• Concentrated in leaves
Chloroplast Structure
Overview of Photosynthesis
• Light Reaction (stage 1)– Thylakoid membranes of granna– Converts light energy to chemical energy– O2 produced as waste product
• Calvin Cycle (stage 2)– Stroma – Synthesizes sugar molecules with CO2 &
energy produced in light reactions
Fig. 7-5-3
H2O
ADP
P
LIGHTREACTIONS
(in thylakoids)
Light
Chloroplast
NADPH
ATP
O2
CALVINCYCLE
(in stroma)
Sugar
CO2
NADP+
Redox (again)
• Recall– Oxidation- loss of e-– Reduction- addition of e-
6 CO2 + 6 H2O C6H12O6 + 6 O2
Reduction
Oxidation
Light Reactions
Wavelength (nm)
10–5 nm
Increasing energy
Visible light
650nm
10–3 nm 1 nm 103 nm 106 nm 1 m
380400 500 600 700 750
Radiowaves
Micro-waves
InfraredX-rays UVGammarays
Light Absorbing Pigments
• Chlorophyll A• Chlorophyll B• Carotenoids
Chlorophyll is excited
Chlorophyllmolecule
Excited state
Ground state
Heat
PhotonPhoton
(fluorescence)
e–
PhotosystemsReactioncenter complex
e–
Primary electronacceptor
Light-harvestingcomplexes
Photon
Transferof energy
Pigmentmolecules
Pair ofChlorophyll a molecules
Th
yla
ko
id m
em
bra
ne
Photosystems
Fig. 7-8a
Stroma
O2
H2O 12 H+
NADP+ NADPHPhoton
Photosystem II
Electron transport chainProvides energy forsynthesis of
by chemiosmosis
+ 2
Primaryacceptor
1
Thylakoidmem-brane
P680
2
4
3Thylakoidspace
e–e–
5
Primaryacceptor
P700
6
Photon
Photosystem IATP
H++
Fig. 7-9
+
O2
H2O12 H+
NADP+ H+ NADPH
+ 2
H+
H+
H+ H+
H+
H+
H+
H+
H+H+
H+
H+
H+ H+
Photosystem II Photosystem IElectrontransport
chain
ATP synthase
LightLight
Stroma (low H+
concentration)
Chloroplast
Thylakoidmembrane
Thylakoid space(high H+ concentration)
ADP + P ATP
Calvin CycleCO2
ATPNADPH
Input
CALVINCYCLE
G3POutput:
Carbon Fixation - Stomata
NADPH
ATP
RuBP
3
P
G3P
P
Input:CO2
1
Rubisco
3 P
Step Carbon fixation
3-PGA6 P
CALVINCYCLE
6
6
6
6
P
Step Reduction
2
2
G3P5 P
3
3
G3P1 P
Glucoseand othercompounds
Output:
Step Release of one
molecule of G3P
1
Step Regeneration of RuBP4
4ATP3
3 ADP
NADP+
6 ADP +
Adaptations
CO2
CALVINCYCLE
Bundle-sheathcell
3-C sugar
C4 plant
4-C compound
CO2
CALVINCYCLE
3-C sugar
CAM plant
4-C compound
Night
Day
Mesophyllcell
CO2 CO2
Photosynthesis and cellular respiration provide energy for life
– Photosynthesis uses solar energy to produce glucose and O2 from CO2 and H2O
– Cellular respiration makes ATP and consumes O2 during the oxidation of glucose to CO2 and H2O
CO2
H2O
Glucose
O2
ATP
ECOSYSTEM
Sunlight energy
Photosynthesis in chloroplasts
Cellular respiration in mitochondria
(for cellular work)
Heat energy
Figure 6.1