An antifungal compound inhibits yeast pyruvate decarboxylase while leaving alcohol dehydrogenase fully active. Under anaerobic conditions, which outcome best predicts how affected yeast cells fare?

Core Concept

Yeast dispose of NADH anaerobically through two linked steps: pyruvate decarboxylase turns pyruvate into acetaldehyde, then alcohol dehydrogenase reduces acetaldehyde to ethanol while oxidizing NADH to NAD+. Blocking the first step eliminates the acetaldehyde acceptor, leaving the intact second enzyme nothing to reduce. NAD+ cannot be recycled, glyceraldehyde-3-phosphate dehydrogenase stalls, and the anaerobic ATP supply fades despite half the pathway remaining functional.