Explain the significance of reformation of NAD by anaerobic

Explain the significance of reformation of NAD+ by anaerobic fermenrtation under conditions in which the cell may have an increase need for ATP, but oxygen supply is limited (or absent).

Solution

Cell needs constant supply of NAD+ to keep glycolysis running. Under anaerobic conditions NADH that is generated during glycolysis cannot be oxidized in mitochondria to NAD+, therefore cell switches to lactate fermentation.

During lactate fermentation, lactate dehydrogenase reversibly converts pyruvate to lactate by using up NADH. This regenerated NAD+ which is then used in glycolysis; supplies energy when oxygen for aerobic respiration is scarce.