If oxygen is not available, pyruvate is converted to which compound during anaerobic glycolysis?

During anaerobic glycolysis, when oxygen is not available, pyruvate is converted to lactic acid. This reaction occurs in the cytoplasm of the cell and serves to regenerate NAD+, which is essential for the continuation of glycolysis. In the absence of oxygen, cells rely on anaerobic pathways to produce ATP, and the reduction of pyruvate to lactic acid allows glycolysis to continue, albeit at a lower yield of ATP compared to aerobic respiration.

The conversion of pyruvate to lactic acid involves the enzyme lactate dehydrogenase, which facilitates the transfer of electrons from NADH back to pyruvate, forming lactic acid and regenerating NAD+. This process is especially important in muscle cells during intense exercise, where oxygen levels may be insufficient for aerobic metabolism.

The other options, such as acetyl CoA and alcohol, are pathways used in aerobic metabolism or in different conditions; for example, acetyl CoA is formed under aerobic conditions when pyruvate is oxidized in the presence of oxygen, and alcohol is produced in alcoholic fermentation (which occurs in yeast, not in human tissues). NADH is an important molecule in the glycolytic pathway but is not a final product of pyruvate metabolism in the