Question

Energy conservation in thioesters, acetyl-CoA and succinyl-CoA:

A. ensure irreversibility of the citrate synthase reaction, in the case of acetyl-CoA
B. ensure the production of GTP in the case of succinyl-CoA
C. in the case of acetyl-CoA is required because OAA concentration in the cell are very low due to the endergonic nature of the malate dehydrogenase reaction
D. occurs through large enzyme complexes
E. All of the above responses are correct and therefore E is my best choice.

Answer 1

Energy conservation in thioesters, acetyl-CoA and succinyl-CoA serves different purposes in the citric acid cycle: ensuring irreversibility of the citrate synthase reaction in the case of acetyl-CoA and enabling the production of GTP in the case of succinyl-CoA.

Step-by-step explanation:

The energy conservation in thioesters, acetyl-CoA and succinyl-CoA serves different purposes in the citric acid cycle.

In the case of acetyl-CoA, energy conservation ensures the irreversibility of the citrate synthase reaction. This prevents the cycle from operating in the reverse direction, where acetyl-CoA would be synthesized from carbon dioxide.

In the case of succinyl-CoA, energy conservation is important for the production of GTP. The hydrolysis of the high-energy thioester bond of succinyl-CoA generates energy that is used to form GTP from GDP and inorganic phosphate.