4.6: Photosynthesis Flashcards
How is photosynthesis a redox reaction? What is being reduced? What is being oxidized?
Photosynthesis converts CO2 into higher-energy carbohydrate molecules which require input of energy.
H2O is oxidized (loses e-) and releases energy.
CO2 is then reduced (gains e-) and gains energy to form carbs.
What is the photosynthetic electron transport chain?
Series of redox reactions that passes electrons from oxidation of water to reduction of CO2.
- Absorption of sunlight for energy to oxidize H2O
- Produce ATP and e- carrier NADPH
- ATP and NADPH are used as energy to synthesize carb using CO2 (Calvin cycle)
Where is the photosynthetic electron transport chain located in for prokaryotes? Eukaryotes?
Pro: Located within the cytoplasm, sometimes directly in the plasma membrane.
Euk: Located within chloroplasts, more specially in the center called the thylakoid membrane.
Grana
Grouped up thylakoid membranes, resembles stacks of pancakes.
Lumen
Inner compartment of the thylakoid membrane.
Stroma
Region surround the thylakoid membrane. Where carbohydrate synthesis takes place.
Why is the photosynthetic electron transport chain sometimes referred to as the ‘Z scheme’?
H20 needs to be oxidized by two photosystems in order to capture enough energy for the production of ATP and NADPH.
Large increase in energy occurs in each of the two systems, and energy decreases as e’ move from one photosystem to the other, resembling a ‘Z’ pattern.
Carboxylation (Carbon cycle)
1st step of the carbon cycle, in which CO2 is added to a 5-carbon molecule (RuBP), forming 3-PGA
Reduction (Carbon cycle)
2nd step of the the carbon cycle, NADPH transfers energy and e- to 3-PGA, forming triose phosphate.
Rubisco
Enzyme that catalyzes the carboxylation step, adding CO2 to RuBP
Regeneration (Carbon cycle)
3rd step of the carbon cycle, most (5/6) of the formed triose phosphate is used to regenerate RuBP, to keep the carbon cycle going. Requires ATP
