Question

During prolonged exercise and fasting, which of these molecules would be used by muscle as a fuel source?

glucose

valine

oxaloacetate

alanine

pyrimidines

Answer 1

Answer - Alanine,if it is a single option answer,Alanine and Valine if multiple options answer.

Carbohydrates>Fats>Proteins from early stages of fasting to prolonged stages.

•In prolonged stages of fasting,the amino acids of proteins enter the gluconeogenesis pathway to form glucose.

For example:

•During prolonged stages of fasting and exercise,Alanine would be used by muscle as fuel source.

•Alanine from the skeletal muscle is taken up by the liver,where alanine gets converted into Pyruvate in a series of reactions.

•In the liver the amino group of alanine is transferred to alpha-ketoglutarate,so that alanine gets converted to pyruvate,and alpha-ketoglutarate to glutamate.

•The Pyruvate then enters the gluconeogenesis pathway where it gets converted into Glucose which enters the respiratory pathway to provide energy.