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19 Cards in this Set
- Front
- Back
Background - what are plants?
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produce their own food, use energy from sun
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Where does photosynthesis occur?
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In choroplasts of mesophyll cells
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Very specific structure
Thylakoids Grana Stroma |
- site of light reactions
- stacks of thylakoids - spaces btw thylakoids |
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The two stages of photosynthesis
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Light reactions
Dark reactions |
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Light reactions
Location Input Output |
thylakoids
- electrons and photons from water, photons from sun, NADP+, ADP + Pi - ATP and NADP, release O2 |
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Dark reactions
Location Input Output |
stroma
- NADPH, ATP, CO2 - sugar, NADP, ADP + Pi |
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Importance of pigments in light reactions:
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diff wavelengths absorbed (we can't see) and reflected (we can see) make different colors
also release electrons |
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Absorption spectra:
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shows wavelengths that have been absorbed by chloroplasts
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Action spectra:
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Shows rate of photosynthesis at different wavelengths
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cholorphyll a vs. chlorophyll b
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a is directly involved, b is an accessory pigment, helping to catch light
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purpose of carotenoids
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photo-protection, which protects plants from damage from light, etc.
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two main parts to a photosystem:
Light harvesting reaction center |
- contain pigments, bound to proteins and transfer photons to reaction center
- two cholophyll a molecules associated with specific proteins, primary e acceptor for electrons |
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Two types of photosystems
Two electron transport chains |
PSI - 700 nm
PSII - 680 nm between PSI and PSII (produces ATP) between PSI and Fb (converts NADP to NADH) |
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PSII - how does it start?
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- activate chlorophyll a electrons, taken by e acceptor
- go through first electron chain, when e is carried off to psI - protons (H+) accumulate in thylakoid space, enhancing proton gradient, used to power ATP synthase and produce ATP |
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PSI - how does it work?
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- e is activated and picked up by primary electron receptor
-2nd electron transport chain to ferredoxin (Fd) -Enzyme NADP+ catalyzes transfer of electrons from Fd to NADP to produce NADPH (used in calvin cycle) |
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Linear vs. Cyclic electron flow
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Linear - uses PSI and PSII to produce ATP and NADPH
Cyclic - uses only PSI and one electron transport chain, producing only ATP |
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DARK REACTIONS
- name the three main phases of the calvin cycle |
1) carbon fixation
- (CO2 ENTERS) - combines with RuBP - reaction is catalyzed by rubisco 2) Reduction - input of phosphate from ATP - electrons from NADPH - 1 3 C molecule leaves to start synthesis of glucose (from 3 CO2 molecules) 3) Regeneration of CO2 acceptor (RuBP) i. 3 atps rearrange to form 3 RUBP, which allows cycle to begin again |
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C3 plant photorespiration
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to protect against damage from excess light, no sugar production
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CAM plants and C4 plants photorespiration
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Crassulacean acid metabolism (CAM) plants store CO2
C4 plants have a prominent bundles sheath cells (Fig. 10.19) Both produce sugars |