Question

What is one piece of evidence suggesting that the conversion of pyruvate to ethanol involves reduction?

A) The release of carbon dioxide during the conversion.
B) The increase in oxygen levels during the process.
C) The formation of water as a byproduct.
D) The absence of oxygen in the reaction.

Answer 1

The conversion of pyruvate to ethanol involves the release of carbon dioxide, indicating a reduction has occurred. Acetaldehyde, produced by decarboxylation of pyruvate, is reduced to ethanol by accepting an electron from NADH.

Step-by-step explanation:

The conversion of pyruvate to ethanol during fermentation is an example of reduction because it involves the gain of electrons. Specifically in this biochemical reaction, a carboxyl group is first removed from pyruvate which releases carbon dioxide, and in the process, the molecule is reduced by one carbon atom to form acetaldehyde. Following this, alcohol dehydrogenase catalyzes the conversion of acetaldehyde to ethanol by transferring an electron from NADH to acetaldehyde, this step oxidizes NADH back to NAD+ and completes the reduction of acetaldehyde to ethanol. The release of carbon dioxide during the conversion is a form of evidence suggesting reduction has occurred.