Question

According to the information provided, what can be concluded about the carbon atoms from acetyl-coA in the citric acid cycle?

A) They are lost as carbon dioxide.
B) They become part of a glucose molecule.
C) They are used in gluconeogenesis.
D) They remain in the acetyl-coA molecule.

Answer 1

The carbon atoms from acetyl-CoA in the citric acid cycle are released as carbon dioxide after a series of reactions within the cycle.

Step-by-step explanation:

The carbon atoms from acetyl-CoA in the citric acid cycle are eventually released as carbon dioxide (CO2).

In the citric acid cycle, the two-carbon acetyl group from acetyl CoA joins with a four-carbon oxaloacetate molecule to form a six-carbon citrate molecule. Through multiple steps in the cycle, each acetyl group is broken down, and two CO2 molecules are released.

These CO2 molecules are not necessarily the original carbon atoms from the acetyl group, as the citric acid cycle includes a series of rearrangements and decarboxylations. Eventually, though, all carbons from glucose, including those in acetyl-CoA, are oxidized to CO2. This process is part of the cell's catabolic pathways, which decompose molecules to release energy, and anabolic pathways, which use intermediates to build other compounds.