Krebs cycle

Question 1

Where does the Krebs cycle occur?

Answer 1

matrix of mitochondria

Question 2

First bit of Krebs cycle -

Answer 2

Coenzyme A carries 2C acetyl groups to the Krebs cycle. Each 2C acetyl group combines with a 4C compound to make a 6C compound. The 6C compound then goes through a circular pathway of reactions that regenerates the 4C compound.

Question 3

How is the 4C compound regenerates in Krebs cycle?

Answer 3

Each 6C compound is decarboxylated and then dehydrogenated. The 5C compound is then decarboxylated. This releases a small amount of energy which can be used to phosphorylate a molecule of ADP, which produces ATP. The 4c compound is then dehydrogenated a further 3 times producing 2 reduced NAD and 1 reduced FAD which recreates the original 4C.

Question 4

Summarise Krebs cycle

Answer 4

For every molecule of glucose entering glycolysis 2 acetyl groups enter the Krebs cycle. Therefore, the Krebs cycle produces 4 CO2, 2 ATP, 6 reduced NAD and 2 reduced FAD per glucose.