In alcohol fermentation, NAD+ is regenerated from NADH by
A) oxidation of ethanol to acetaldehyde.
B) oxidation of pyruvate to acetyl CoA.
C) reduction of pyruvate to lactate.
D) reduction of acetaldehyde to ethanol.
E) reduction of acetyl CoA to ethanol.

Question

Quizplus · Accepted Answer

In alcohol fermentation, NAD+ is regenerated by the reduction of acetaldehyde to ethanol. Pyruvate is first converted to acetaldehyde in the presence of the enzyme pyruvate decarboxylase, releasing CO2. Then, the acetaldehyde is reduced to ethanol by the enzyme alcohol dehydrogenase, which uses NADH as a reducing agent. This reaction regenerates NAD+ so that glycolysis can continue in the absence of oxygen.

In Alcohol Fermentation, NAD+ Is Regenerated from NADH by