What is pyruvate mainly converted into when oxygen is available?

When oxygen is available, pyruvate is mainly converted into Acetyl-CoA. This conversion occurs in a process known as pyruvate decarboxylation, which takes place in the mitochondria of eukaryotic cells. During this process, pyruvate, which is generated from glycolysis, loses a carbon dioxide molecule and is then linked to coenzyme A to form Acetyl-CoA.

Acetyl-CoA then enters the citric acid cycle (Krebs cycle), where it plays a crucial role in cellular respiration, contributing to the production of ATP through further oxidation. This process is vital for efficient energy production when oxygen is present, as it allows for complete aerobic respiration.

In contrast, if oxygen were not available, pyruvate would be converted into lactic acid in animals or ethanol in yeast, which is a form of anaerobic respiration. Additionally, Acetyl-CoA is not directly converted into citric acid or glucose, making its formation from pyruvate a key step in aerobic metabolism.