Question

Choose the correct order of events in the Kreb's cycle:

Answer 1

Pyruvate is split, citric acid is formed, coenzyme A is added 

Answer 2

The right answer is Pyruvate is split, citric acid is formed, coenzyme A is added

*Decarboxylation of pyruvate, is the reaction catalyzed by pyruvate dehydrogenase complex linking glycolysis to the Krebs cycle by converting pyruvate to acetyl-CoA.

*Citrate synthase condenses oxaloacetate and acetyl-CoA into citrate with release of coenzyme A. A transient intermediate, citroyl-CoA, is formed. The thioester linkage of acetyl-CoA is a high-potential hydrolysis bond. The coupling of the hydrolase and synthase activities makes the synthesis reaction thermodynamically possible.

*In the oxidative decarboxylation of α-ketoglutarate, the α-ketoglutarate dehydrogenase complex catalyzes the oxidative decarboxylation of α-ketoglutarate to succinyl-CoA with production of NADH + H + and evolution of CO2. It is a reaction similar to that converting pyruvate to acetyl-CoA catalyzed by the pyruvate dehydrogenase complex.