What happens to pyruvate under anaerobic conditions?

Under anaerobic conditions, the primary fate of pyruvate is to be converted to lactate. This process occurs when there is insufficient oxygen available to enter the aerobic pathway of cellular respiration, primarily taking place in muscle cells during high-intensity exercise or in certain microorganisms.

When pyruvate is generated through glycolysis and oxygen is limited, the cell needs a way to regenerate NAD⁺ to maintain glycolysis and ensure a continuous supply of energy. The conversion of pyruvate to lactate, catalyzed by the enzyme lactate dehydrogenase, allows this regeneration to take place. This lactate can then either accumulate within the muscle tissue or be transported to the liver, where it can be converted back into glucose through gluconeogenesis.

In contrast, the other potential pathways indicated by the other options do not occur under anaerobic conditions. For example, the conversion of pyruvate to glucose typically occurs during gluconeogenesis in the liver and requires oxygen and an energy investment. The conversion to fatty acids occurs in a process involving excess energy and a different metabolic state, not typically associated with anaerobic conditions. Lastly, converting pyruvate to acetic acid is more relevant to the aerobic pathway when pyruvate enters the Krebs