Which intermediate is produced during ethanol fermentation?

During ethanol fermentation, a specific pathway involving the conversion of glucose to ethanol and carbon dioxide occurs. This process is crucial for organisms like yeast that perform anaerobic respiration.

The correct intermediate produced is acetaldehyde. In the fermentation process, glucose is initially converted into pyruvate through glycolysis. Pyruvate is then decarboxylated, releasing carbon dioxide to form acetaldehyde. This acetaldehyde is subsequently reduced by the enzyme alcohol dehydrogenase, ultimately leading to the production of ethanol. The conversion of pyruvate to acetaldehyde is a critical step that allows the process of fermentation to occur, particularly in the alcoholic fermentation pathway.

The other intermediates listed do not directly relate to ethanol fermentation. Fructose 6-phosphate, for example, is an intermediary of glycolysis and not specifically related to ethanol production. Lactate is produced during lactic acid fermentation, serving different metabolic needs. Glyceraldehyde-3-phosphate is also a glycolytic intermediate before pyruvate formation. In the context of ethanol fermentation specifically, acetaldehyde is the key player produced during the conversion stages after glycolysis.