Suppose that there is a mutation in a single-celled organism where the Krebs cycle (TCA/Citric Acid Cycle) doesn't happen. What would be the consequences for that organism? How would their metabolism be similar to ours? How would it be different?
Because citrate synthase is inhibited by the final product of the citric acid cycle as ATP, ADP (adenosine diphosphate) works as an allosteric activator of the enzyme as ATP is formed from ADP. Therefore, the rate of the cycle is reduced when the cell has a high level of ATP.