Lecture 11 - Fixation Stage of Calvin Cycle

Question 1

Step 1

Answer 1

Ribulose 5-P -> ribulose 1,5-bisP

Question 2

Cofactor of step 1

Answer 2

ATP -> ADP

Question 3

Enzyme of step 1

Answer 3

Ribulose phosphate kinase

Question 4

Step 2

Answer 4

Ribulose 1,5-bisP -> (2x) 3-phosphoglyercate

Question 5

Enzyme of step 2

Answer 5

Ribulose bisphosphate carboxylase

Question 6

Cofactor of step 2

Answer 6

CO2 in

Question 7

What is another name for ribulose bisphosphate carboxylase?

Answer 7

Rubisco

Question 8

What is the most abundant protein in nature?

Answer 8

Rubisco

Question 9

Step 3

Answer 9

(2x) 3-phosphoglycerate -> (2x) 1,3-bisphosphoglycerate

Question 10

Enzyme of step 3

Answer 10

3-phosphoglycerate kinase

Question 11

Is step 3 reversible?

Answer 11

Yes

Question 12

Is step 2 reversible?

Answer 12

No

Question 13

Is step 1 reversible?

Answer 13

No

Question 14

Cofactor of step 3

Answer 14

2 ATP -> 2 ADP

Question 15

Step 4

Answer 15

(2x) 1,3-bisphosphoglycerate -> (2x) glyceraldehyde-3-P -> dihydroxyacetone P

Question 16

Enzymes of step 4

Answer 16

Glyceraldehyde-3-P dehydrogenase and triose phosphate isomerase

Question 17

Are the enzyme of step 4 reversible?

Answer 17

Yes

Question 18

Cofactor of step 4

Answer 18

Cofactor for G-3-P dehydrogenase is 2 Pi out and 2 NADPH + 2 H+ -> 2 NADP+

Question 19

What happens to the products of the fixation stage?

Answer 19

• 5 of the 6 C3 molecules are recycled back into the pathway through the rearrangement stage
• 1 C3 (profit) is used to make glucose through gluconeogenesis