Which of the following is a main source of acetyl CoA?

Acetyl CoA is a central metabolite in various biochemical pathways, primarily functioning as a key entry point into the citric acid cycle (Krebs cycle). One of the main sources of acetyl CoA is indeed the conversion of pyruvate.

During glycolysis, glucose is broken down into pyruvate. When oxygen is available, pyruvate is then transported into the mitochondria where it undergoes a transition reaction, converting it into acetyl CoA through decarboxylation. This process also produces NADH and releases carbon dioxide. As such, the conversion of pyruvate is a crucial step for entering the citric acid cycle, highlighting the importance of pyruvate as a precursor to acetyl CoA.

In contrast, while triglycerides can be hydrolyzed to glycerol and fatty acids, and fatty acids are then broken down into acetyl CoA via β-oxidation, the most direct and readily utilized source of acetyl CoA in the context of glucose metabolism is indeed from pyruvate. Therefore, the conversion of pyruvate to acetyl CoA stands out as a primary pathway contributing to the formation of this important molecule.