Question

If glucose is the sole energy source, what fraction of the carbon dioxide exhaled by animals is generated only by the reactions involved in oxidation of pyruvate to acetyl coa?

Answer 1

We have to know what fraction of the carbon dioxide exhaled by animals is generated only by the reactions involved in oxidation of pyruvate to acetyl coa.

The fraction is: 1 CO₂ per puruvate molecule.

Pyruvate oxidation takes place in the mitochondrial matrix, before chemical reactions begins, pyruvate enters the mitochondrion crossing the inner membrane and arriving at the matrix.

Oxidation of pyruvate results acetyl coenzyme A after release of one molecule of CO₂.

Answer 2

Answer:

1/3

Explanation:

Pyruvate is produced by the glycolysis in cytoplasm. The oxidation of pyruvate takes place in mitochondrial matrix.  

Pyruvate is converted to acetyl-CoA in the reaction given below:

Pyruvate + NAD⁺ + CoA-SH ⇒ acetyl-CoA + NADH + CO₂

1 molecule of carbon dioxide is eliminated from 1 molecule of pyruvate.

Also,

2 molecules of carbon dioxide is eliminated from 2 molecules of pyruvate (as glucose on glycolysis yields 2 molecules of pyruvate).

Also, acetyl-CoA further goes into the citric acid cycle and produces 2 molecules of carbon dioxide.

Thus pyruvate produces total 3 molecules of CO₂  and hence glucose produces 6 molecules of CO₂ (as glucose on glycolysis yields 2 molecules of pyruvate)

Thus,

Fraction = 2/6 = 1/3