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Photoautotroph
Use light as a source of energy¨Green plants, algae, cyanobacteria
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Photosynthesis
photo energy to solar energy
plants,algae, certain other protists, and some prokaryotes
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formula
CO2 + H2O + light energy → C6H12O6 + O2 + H2O
- CO2 is reduced
- H2O is oxidized
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Chloroplast
green color is from chlorophyll
split water
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stomata
where O2 and CO2 is exchanged
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Mesophyll
where chloroplasts are found
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thylokoid
- in chloroplast
- stacked columns known as grana
has outer and inner membrane space
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Stroma
fluid filled region between thylakoid membrane and inner membrane
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two stages of photosynthesis
light reaction and calvin cycle
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light reaction
Release O2
Reduce NADP+ to NADPH
Generate ATP from ADP by photophosphorylation
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calvin cycle
- in stroma
- forms sugar from CO2, using ATP and NADPH
The Calvin cycle begins with carbon fixation, incorporating CO2 into organic molecules
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light energy
behaves like photons (shorter = more energy)
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photosynthetic pigments
absorb some light energy and reflect others (why leaves are green
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absorption of pigments
boosts electrons to higher energy levels
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carotenoids
absorb yellow an orange and other harmful things to cell
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chlorophyll a
main photosynthetic pigment
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cholorophyl b
broadens spectrum
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photosystems
PSII FIRST then PSI (PS1 discovered first)
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ATP synthesis
via atp synthesis
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H+ gradient
across thylakoid membrane
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cyclic
uses only PSI no NAPDH
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non cyclic
- don't get H2O oxydized
- makes ATP and NADPH
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6Co2 + 6 RuBP = 12 PGaL
- 12 Pgal - 2 for glucose = 10 pgal
- to make 6 rupb
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3 phases of calvin cycle
- carbon fixation
- Reduction and carbohydrate production
- Regeneration of RuBP
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photorepiration
- fixes O2 via RuPB BUT it's not remade :/
- only makes ATP
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C3 plant
- CO2 directly from the air into calvin cycle
- ie soybean, wheat, rice, etc
- BUT stomata closed to converse water on hot dry days (goes into photo respiration)
better in cooler temp b/c uses less energy
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C4 plant
- has the bundle sheath (2 cell layer organization)
- can keep stomata closed BUT make glucose because 4 carbon molecule in sheath cells
- ie corn, sugar cane, etc
good in hot dry places
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CAM plant
- keep stomata closed in day and open at night
- store CO2 at night and use it in the day BUT is in the mesophyl cell
- ie pineapple, cacti, etc
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