Calvin cycle (PS)

Question 1

what is CO2 reduced to in Calvin cycle

Answer 1

G3P

Question 2

what is the energy source in Calvin cycle

Answer 2

ATP (product of light rxns)

Question 3

what is the reducing agent of CO2 reduction

Answer 3

NADH (product of light rxns)

Question 4

for the synthesis of 1 G3P, how many times does cycle occur

Answer 4

3 (g3p is a 3 carbon molecule)

Question 5

what are the three phases of the Calvin cycle

Answer 5

1. carbon fixation (catalyzed by rubisco)
2. reduction of CO2 to sugar
3. regeneration of CO2 acceptor (RuBP)

Question 6

what happens during carbon fixation (3)

Answer 6

1. 3 CO2 enter
2. CO2 attached to RuBP (5C) by enzyme rubisco
3. 6C intermediate splits in 2
   (each CO2 gets 2 3-phosphoglycerate) (each is 3C)

Question 7

what happens during carbon reduction

Answer 7

1. 3-phosphoglycerate receives phosphate from ATP => produces 1,3-biphosphoglycerate
2. NADPH (2e) reduces 1,3-biphosphoglycerate to glyceraldehyde 3-phosphate (G3P)

Question 8

overall from carbon fixation and carbon reduction:

Answer 8

3 CO2 + 3 RuBP –> 6 G3P

Question 9

what does regeneration of RuBP entail

Answer 9

• 1 G3P exits cycle, used to make glucose/other organic molecules
• 5 G3P used to regenerate RuBp (5C)

Question 10

what is total input of calvin cycle

Answer 10

3 CO2
9ATP
6NADPH

Question 11

what is output of Calvin cycle

Answer 11

1 G3P