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27 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Photosynthesis |
Conversion of light E into chemical E (sugar). Has 2 parts, Light Reaction & thr Calvin Cycle.
Needs CO2, H2O and sunlight E. Redox (reduction of CO2 & oxidation of H2O) reaction.
Takes place in chloroplasts in eukaryotes |
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Organisms who do photosynthesis |
Cyanobacteria, algae, & plants |
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Organisms who use chloroplasts |
Algae & plants |
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Over veiw of photosynthesis |
6 carbon dioxide molecules + 6 water molecules --> 1 6 carbon sugar + 6 oxygen molecules (from H2O as waste product)
6 C SUGAR ALWAYS PRODUCED FROM CALVIN CYCLE & ALWAYS BREAKS IN HALF TO TWO 3C SUGARS |
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CO2 reduction |
CO2 is reduced (gains electron & energy) into a sugar |
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H2O Oxidation |
H2O oxidizes (loses electrons & energy) & gives them to CO2. |
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Electron transport chain |
H2O oxidizes and gives its electrons to CO2 (causing reduction) |
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Light reaction |
Sunlight E (absorbed by chlorophyll) enables water electrons to leave water and join carbon dioxide (electron transport chain). Electron movement used to produce ATP & NADPH. O2 produced at this point from water |
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Calvin cycle |
Needs per cycle: 1 CO2 1 RuBP 1 Rubisco 2 NADPH 2 ATP
Forms per 3 cycles (1RuBP can process 2 CO2): 1 6-C sugar --> 2 3-C sugars ( glyceraldehyde 3-phosphate).
Sugar used in cellular respiration or makes organic molecules (lipids, amino acids, etc)
3 step process: 1. CO2 & RuBP combine in Rubisco's active site. 6-C sugar forms (ustable), immediately breaks into 2 3-C sugars (3-phosphoglycerate/3PG).
2. H+ & 2 e- added by 1 NADPH and Phosphate group added by 1 ATP to each 3PG (so 2 ATP & 2 NADPH per 1 CO2) to form glyceraldehyde 3-phosphate (G3P).
3. RuBP recharged for next CO2. Need 5 G3P 9 ATP 6 NADPH to regenerate 3 RuBP. 3 RuBP makes 6 G3P |
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Thylakoid membrane |
In chloroplast. Electron transport chain and chlorophyll pigment located here. Light reactions happens here. |
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Stroma |
Colorless fluid in chloroplast, surrounds the Thylakoid membrane. The calvin cycle takes place here. |
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Light |
Different wavelengths = different colours. When it hits matter, it's: Reflected (colour you see) Transmitted (goes thru) Absorbed |
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Pigment |
Molecule that absorbs certain wavelengths (colours). |
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Chlorophyll |
Absorbs blue & red. Reflects/transmits green |
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Carotenoids |
Absorbs blue & green Reflects yellow & orange |
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RuBP |
Ribulose bis phosphate. Start/end molecule in Calvin cycle. Is a 5-C sugar. |
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Rubisco |
Enzyme that binds RuBP & CO2 in calvin cycle |
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Challenges to photosynthetic efficiency |
1. Too much light E 2. Photorespiration |
2 things |
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Too much light E & 2 solutions |
Plant can't process e- fast enough. e- combines w O2 (forms free radicals) and damages plant molecules.
Solution: 1. Pigments absorb E from Chlorophyll & release it as heat 3. Detoxifies reactive molecules w anti-oxidants (like vitamin C) |
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Photorespiration |
Occurs when low [CO2] and high [O2] in cell. Enzyme rubisco accidentally accepts an O2 instead of CO2 into active site. Then binds O2 to RuBP --> RuBP breaks apart & is lost. Also no sugar made.
Can lose up to 50% of sugars this way. |
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How did photorespiration occur? |
Calvin Cycle/Photosynthesis evolved when there was little/no O2 in atmosphere/ocean. Has not evolved a better way yet |
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How much solar E that hits a leaf is converted into carbohydrates/sugar? |
1-2% |
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NADP+ + 2e- + H+ --> |
NADPH |
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ADP + H+ + phosphate ---> |
ATP. Proton/H+ used to glue phosphate group to ADP |
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How do pigments absorb E? |
Absorb E by having e- bumped up to a higher E shell. E always stored in electrons as potential E |
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When is photorespiration at its worst |
Worse on hot/sunny days. Leaf closes stomata (leaf pore) to save water and traps O2 as well. |
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How do plants not run out of e- during photosynthesis? |
e- taken from H+ in H2O. So long as plant has new H2O it will never run out of e- |
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