Krebs cycle

Question 1

Where does the Krebs cycle happen?

Answer 1

In the matrix

Question 2

Stage 1

Answer 2

The 2 carbon Acetate carried in by the coenzyme A joins with a 4 carbon compound (oxaloacetate) to form a 6 carbon compound. CoA goes back to be used again in the Link Reaction.

Question 3

Stage 2

Answer 3

Decarboxylation occurs so a carbon is lost from the 6 carbon compound to make a 5 carbon. It is then oxidised and loses a hydrogen which is accepted by NAD to make a NADH

Question 4

Stage 3

Answer 4

The 5 carbon molecule is then decarboxylated again to make a 4 carbon molecule. It is then oxidised and loses 2 hydrogens to NAD to make 2 NADH and it loses 1 hydrogen to FAD to make FADH. One molecule of ATP is also formed by substrate level phosphorylation.

Question 5

What are the products of the Krebs Cycle?

Answer 5

Per cycle:
2 CO2
3 NADH
1 FADH
1 ATP
Per glucose:
4 CO2
6 NADH
2 FADH
2 ATP