What serves as a precursor in the synthesis of acetyl-CoA?

What serves as a precursor in the synthesis of acetyl-CoA?

• A. Oxaloacetate
• B. Pyruvate
• C. Choline
• D. Acetyl-CoA

Answer: (B)

The immediate precursor to acetyl-CoA is pyruvate. In the mitochondria, pyruvate is converted to acetyl-CoA by the pyruvate dehydrogenase complex, releasing CO2 and generating NADH in the process. This step links glycolysis to the TCA cycle and is effectively irreversible and tightly regulated by the cell’s energy state. Oxaloacetate is a TCA intermediate that combines with acetyl-CoA to form citrate, not a precursor to acetyl-CoA. Choline is unrelated to the formation of acetyl-CoA, serving other roles like acetylcholine synthesis and phospholipid metabolism. Acetyl-CoA is the product here, though other routes (such as fatty acid beta-oxidation or certain amino acids) can also supply acetyl-CoA indirectly.

The immediate precursor to acetyl-CoA is pyruvate. In the mitochondria, pyruvate is converted to acetyl-CoA by the pyruvate dehydrogenase complex, releasing CO2 and generating NADH in the process. This step links glycolysis to the TCA cycle and is effectively irreversible and tightly regulated by the cell’s energy state. Oxaloacetate is a TCA intermediate that combines with acetyl-CoA to form citrate, not a precursor to acetyl-CoA. Choline is unrelated to the formation of acetyl-CoA, serving other roles like acetylcholine synthesis and phospholipid metabolism. Acetyl-CoA is the product here, though other routes (such as fatty acid beta-oxidation or certain amino acids) can also supply acetyl-CoA indirectly.