3.5 Contd: Photosynthesis - Calvin Cycle Flashcards
The Calvin Cycle is ___ electron flow.
Cyclic
The Calvin Cycle uses __ and ____to reduce ____ to ___.
- ATP
- NADPH
- CO2
- sugar (G3P)
To synthesize 1 G3P molecule, how many times must the Calvin Cycle take place?
3
G3P has how many carbons?
3
What are the three phases of the Calvin Cycle?
- Carbon fixation (attach smth to CO2)
- Reduction (reduce CO2 to some sort of carb)
- Regeneration of RuBP
What occurs in carbon fixation? (3)
- CO2 is incorporated into the Calvin Cycle ONE AT A TIME (1C)
- Each CO2 attaches to a molecule of RuBP (5C)
- catalyzed by the enzyme rubisco - Forms 3-phosphoglycerate (3PG or PGA)
What is RuBP?
Ribulose 1,5 biphosphate
What occurs in reduction?
- Esch molecule of 3 - phosphoglycerate is phosphorylated by ATP
- Becomes 1,3 - biphosphoglycerate
- NADPH molecules donate electrons to form 1,3 - biphosphoglycerate
- Reduces to G3P (add a P and a H+ to form G3P)
What occurs in regeneration of RuBP?
- 5 G3P molecules (15C total) are used to regenerate molecules of RuBP (5C)
- Uses 3 ATP for regeneration
- Cycle is now ready to take CO2 again
What are the inputs of the Calvin Cycle per 3 turns? (3)
- 3 CO2
- 9 ATP
- 6 NADPH
Note that inputs and outputs must be doubled for 6 CO2 cuz glucose has 6 carbin right
What are the outputs of the Calvin Cycle per 3 turns?
- 1 G3P
- 9 ATP
- 6 NADP+
So our input per 3 turns of the Calvin cycle is 9 ATP. For one glucose molecule, we need 18 ATP. Where do these Atp go to?
- 12 for attaching hydrogens
- 6 for regenerating smth I forgot
What is a summary of the Calvin Cycle?
- Use NADPH, ATP and CO2
2. Produces a 3-C sugar G3P
G3P is a building block for other ___
Carbs, lipids, etc.
