Question

Carbons from acetyl CoA are transferred to the citric acid cycle. Which is the first round of the citric acid cycle that could possibly release a carbon atom originating from this acetyl CoA?

Answer 1

Answer:

In the third step of the citric acid cycle, the oxidation of isocitrate takes place and one molecule of carbon dioxide is released.

Explanation:

In the first step of citric acid cycle, acetylCoA combines with a four-carbon molecule, oxaloacetate, forming a six-carbon molecule, citrate.

In the second step, the citrate in the presence of enzyme anicotase is converted into isocitrate.

In the third step, the oxidation of isocitrate takes place and one molecule of carbon dioxide is released leaving behind one five-carbon molecule called as α-ketoglutarate. During this step, NAD⁺ is reduced to form NADH.

This is first round of the citric acid cycle that could possibly release a carbon atom originating from this acetyl CoA.

On series of reaction, another carbon dioxide molecule also being relased and oxaloacetate is regenerated again.