Final answer:
Pyruvate generated in glycolysis is converted into acetyl CoA before entering the Krebs cycle. This process involves oxidative decarboxylation and results in the production of NADH, FADH2, and ATP.
Step-by-step explanation:
The pyruvate generated in glycolysis undergoes a three-step process before it enters the Krebs cycle. First, it is converted by the enzyme pyruvate dehydrogenase into a two-carbon acetyl coenzyme A (acetyl CoA) molecule in the mitochondrial matrix. This reaction releases carbon dioxide and transfers two electrons that combine with NAD+ to form NADH. Then, the acetyl CoA enters the Krebs cycle by combining with oxaloacetate to form citrate. This process generates high-energy NADH, FADH2, and ATP molecules.