Final answer:
The step in ETOH metabolism occurring in the cytosol is catalyzed by alcohol dehydrogenase, which converts ethanol into acetaldehyde. The correct option is a.
Step-by-step explanation:
The step in ethanol (ETOH) metabolism that occurs in the cytosol is catalyzed by the enzyme alcohol dehydrogenase.
During the metabolism of ethanol, alcohol dehydrogenase in the liver converts ethanol into acetaldehyde. Acetaldehyde is highly toxic, and therefore, it is immediately processed by acetaldehyde dehydrogenase (ALDH), which converts acetaldehyde into acetate, a non-toxic molecule.
This reaction happens in the cytosol of liver cells. It's important to note that subsequent steps, such as the conversion of acetate to acetyl-CoA, occur in the mitochondria, not in the cytosol. The correct option is a.