<prompt> In glycolysis which of the following is not involved?Pyruvate dehydrogenasePhosphofructokinaseGlucokinasePyruvate kinase  <response>: Ans. A Pyruvate dehydrogenase The enzyme Pyruvate dehydrogenase irreversibly converts pyruvate, the end product of glycolysis, into acetyl CoA, a major fuel for the TCA cycle and the building block for fatty acid synthesis Thus, this enzyme pyruvate dehydrogenase is utilized in citric acid cycle and fatty acid synthesis. The reaction of pyruvate dehydrogenase, forming acetyl- CoA, is irreversible, and for every two carbon unit from acetyl-CoA that enters the citric acid cycle, there is a loss of two carbon atoms as carbon dioxide before oxaloacetate is reformed. This means that acetyl-CoA and hence any substrates that yield acetyl-CoA can never be used for gluconeogenesis. 