What significant change happens to NADH during the lactic acid fermentation pathway?

During the lactic acid fermentation pathway, NADH undergoes a crucial transformation. This process involves the oxidation of NADH, resulting in it losing electrons, which in turn converts NADH back into NAD+. This regeneration of NAD+ is essential because it allows glycolysis to continue, as NAD+ is needed to accept electrons during the glycolytic pathway.

In environments with low oxygen (anaerobic conditions), organisms utilize lactic acid fermentation to produce energy. By converting NADH to NAD+, the cell can keep producing ATP through glycolysis. This step is vital for sustaining energy production when aerobic respiration is not possible.

Other options do not accurately represent what occurs to NADH during fermentation. For instance, NADH is not synthesized into glucose, it does not directly convert into ATP, and it does not combine with pyruvic acid; rather, it donates its electrons to pyruvic acid to form lactic acid while regenerating NAD+. This key transformation allows the continuation of metabolic processes under anaerobic conditions.