One consequence of ethanol addiction is fatty liver disease, an illness in which liver cells
accumulate large amounts of triacylglycerols, the esters derived from glycerol and fatty acids.
Ethanol is oxidized in the cytoplasm of liver cells by alcohol dehydrogenase and aldehyde
dehydrogenase to yield acetate and 2 NADH. Acetate is then transported into the
mitochondrion, where it is converted to acetyl-CoA and metabolized in the citric acid cycle.
When alcohol is consumed in excessive quantities, the resulting high levels of NADH cause
metabolic abnormalities, one of which is high levels of fatty acid synthesis. Fatty acid
synthesis, also a cytoplasmic process, uses acetyl-CoA as a substrate and NADPH as a
reducing agent. Speculate about how a high level of cytoplasmic NADH provides a source of
NADPH for fatty acid synthesis.