In yeast, what is pyruvate converted into during ethanol fermentation?

During ethanol fermentation in yeast, pyruvate is converted into ethanol and carbon dioxide. This process begins after glycolysis, where glucose is broken down into pyruvate. In the absence of oxygen, yeast cells undergo fermentation to regenerate NAD+, which is necessary for glycolysis to continue producing ATP, the energy currency of the cell.

In the first step of this fermentation, the pyruvate is decarboxylated, resulting in the release of carbon dioxide. Subsequently, the resulting acetaldehyde undergoes reduction, which involves the addition of electrons, to form ethanol. This entire process allows yeast to survive in anaerobic conditions by generating energy efficiently without oxygen and also producing ethanol, which is often significant in brewing and winemaking.

Thus, the correct answer accurately reflects the end products of yeast fermentation, capturing the essence of how yeast cells metabolize sugar in low oxygen environments.