Question

Conversion of pyruvic acid into ethyl alcohol is mediated by

• A. phosphatase
• B. dehydrogenase
• C. decarboxylase and dehydrogenase
• D. catalase

Answer 1

The correct option is C decarboxylase and dehydrogenase

The process in which pyruvic acid is converted to ethyl alcohol (ethanol) is known as alcoholic fermentation which is a type of anaerobic respiration.

Decarboxylation of pyruvic acid is the first step of alcoholic fermentation. The three carbon pyruvic acid loses a molecule of carbon dioxide to form the two carbon acetaldehyde. This reaction is catalysed by the enzyme pyruvate decarboxylase.

Regeneration of ${\mathrm{NAD}}^{+}$ occurs in the second step of alcoholic fermentation where acetaldehyde accepts the electrons and hydrogen from NADH to form ethanol. Hence, ${\mathrm{NAD}}^{+}$ is regenerated in this process. Alcohol dehydrogenase catalyses this second step of the reaction.