In the context of cell metabolism, what compound is produced from pyruvate in the Krebs cycle?

• A. Oxaloacetate
• B. Acetyl-CoA
• C. Lactic Acid
• D. Glycerol

Answer: (B)

When pyruvate enters the Krebs cycle, it is converted into Acetyl-CoA. This conversion is a crucial step that occurs before pyruvate can be fully oxidized in the Krebs cycle, also known as the citric acid cycle.

Pyruvate, which is generated from glycolysis, undergoes decarboxylation in a process facilitated by the enzyme pyruvate dehydrogenase. During this reaction, one carbon atom is removed from pyruvate (a three-carbon compound) as carbon dioxide, resulting in the formation of a two-carbon compound, Acetyl-CoA. Additionally, this reaction also reduces NAD+ to NADH, making Acetyl-CoA an important linkage between glycolysis and the Krebs cycle, as well as a vital metabolic intermediate that feeds into the cycle to eventually produce energy in the form of ATP, along with NADH and FADH2.

Understanding this conversion is key to grasping how cells generate energy under aerobic conditions, and highlights the importance of Acetyl-CoA in cellular metabolism.