Final answer:
The step in ethanol metabolism that takes place in the cytosol is the conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate, producing NADH.
Step-by-step explanation:
Step in Ethanol Metabolism in the Cytosol
The step in ethanol (ETOH) metabolism that occurs in the cytosol is part of the glycolytic pathway, specifically during the conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate by the enzyme glyceraldehyde-3-phosphate dehydrogenase. This reaction results in the reduction of NAD+ to NADH, which is significant because the NADH produced in the cytosol during glycolysis can be transported to the mitochondria. There, it enters the electron transport chain (ETC), where it ultimately contributes to the production of a net gain of 36 ATP when oxidized. This energy yield is facilitated by shuttles such as the glycerol phosphate shuttle, rather than the malate-aspartate shuttle, to transport NADH across the mitochondrial membrane due to its impermeability.