Final answer:
Coenzyme A possesses a thiol group that enables the formation of a high-energy thioester bond with pyruvate, resulting in the production of acetyl CoA, essential for the Krebs cycle and energy production.
Step-by-step explanation:
Coenzyme A (CoA) has a thiol group that forms a high-energy thioester bond when bound to pyruvate to form acetyl CoA. This process occurs during the catabolism of carbohydrates when pyruvate, a product of glycolysis, is oxidized. The reactive thiol group (-SH) of CoA attacks the pyruvate molecule, leading to the formation of acetyl CoA. This transformation is crucial as the acetyl CoA then enters the citric acid cycle (Krebs cycle), carrying the acetyl group derived from pyruvate for further catabolism. In addition, a molecule of carbon dioxide is released and two high-energy electrons are captured by NAD+, forming NADH, which later contributes to ATP production. The process involves various enzymes such as pyruvate dehydrogenase and thiokinase, and the produced acetyl CoA has various functions, including the delivery of acetyl groups to the Krebs cycle for energy extraction.