Question

2. At what point do the carbon atoms of each of the following amino acids enter metabolic pathways for the production of energy? State citric acid cycle, etc.

a. valine:

b. proline:

c. glycine:

Answer 1

The process by which the amino acids entering  the pathways is primarily by degrading the amino group of these amino acids and the carbon skeletons to take part in  the energy production process for oxidation.

This depends on the number of carbon atom that may be present after the amino group degradation.

Therefore ,

Valine :Valine is converted to succinyl CoA and this an intermediary step in the Kreb’s cycle

Proline : Proline is converted to glutamate which enters the Citric acid cycle

Glycine: Glycine first is converted to serine by an extemporaneous reaction which is further converted to pyruvate and it enters the pathway in the step of pyrubate oxidation