- Photosystem II is 'excited' because it absorbs a light photon (P680 wavelength) and pulls electrons from H2O (causing hydrogens to break apart from oxygen) and PSII gains electrons. Process of breaking water apart is called photolysis.
Oxidation: element gains an electron
Reduction: element loses an electron
- electrons transferred to PQ, then b6-f and forms a bridge to allow hydrogen atoms to enter the leaf, then electrons transfer to PC
- PSI gets 'excited' with light photon (P700 wavelength) and then becomes oxidized, then electrons pass through Fd, FNA, and NADP
- Once NADP becomes oxidized, hydrogen pair (H2) breaks apart and bonds with NADP+ and becomes NADPH
- ADP synthase bonds with Adenine and 2 phosphate molecules to form ADP; they spin quickly allowing excess hydrogen to exit the leaf.
Then 3rd phosphate atom bonds with ADP, forming ATP (process called Chemiosmosis)
Light-independent reaction: reaction that assimilates CO2 to produce an organic molecule
- carbon dioxide fixation - carbon dioxide chemically bonds with RuBP (ribulose 1,5-biphosphate) breaks into 2 stable PGA's (3-phosphoglycerate). Ribisco helps catalyze this reaction
CO2 + RuBP -> unstable C6 -> PGA
- PGA's are activated by ATP (add phosphate group) and then reduced by NADPH (removes phosphate group). NADPH loses its hydrogen. New compound formed, G3P. G3P may be used to make glucose and carbohydrates.
- reduced G3P make more RuBP - energy (ATP) is required to break and reform the bonds to make 5 carbon RuBP from G3P
- Calvin cycle must be completed 6 times to synthesize 1 molecule of glucose
- 12 G3P that are produced in the 6 cycles, 10 are used to generate RuBP, and 2 are used to make 1 glucose.
6CO2 + 18 ATP + 12 NADPH + water -> 2 G3P + 16 Pi + 18 ADP + 12 NADP+
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