Question

Each round of the citric acid cycle begins when the four-carbon molecule oxaloacetate is converted to the six-carbon molecule citrate. As the cycle progresses, two carbons are eliminated to regenerate the oxaloacetate. The added carbon is supplied by _____ and the two eliminated carbons are released as _____.
A. CO2; acetyl-CoA
B. ATP; acetyl-CoA
C. Acetyl-CoA; CO2
D. CO2; NADH
E. CO2; pyruvate

Answer 1

Answer:

The added carbon is supplied by acetyl CoA and the 2 eliminated carbons are released as CO2.

Explanation:

TCA cycle or citric acid cycle occurs in the mitocondrial matrix.

           The ist step of TCA cycle deals with the formation of citrate molecule bt the addition of Acetyl CoA with oxaloacetate. The acetyl CoA is a 2 carbon compound formed from pyruvate by the catalytic activity of pyruvate dehydrogenase .

          The 2 eliminated carbons are released as carbon di oxide or CO2.The CO2 molecule is eliminated during the formation of alpha ketoglutarate from isocitrate .The second CO2 molecule is eliminated when alpha ketoglutarate is converted to succinyl CoA.