NEST2026BiologyRespiration in Plants
The fate of a cell in which pyruvate dehydrogenase is completely inhibited will be:
Options
- APyruvate accumulates and enters the Krebs cycle via an alternative pathway, yielding 32 ATP per glucose molecu
- BGlycolysis stops due to NAD ^+ depletion, and no ATP is produced.
- CGlycolysis continues with NAD ^+ regeneration via lactate fermentation, yielding 2 ATP per glucose molecule.
- DPyruvate is converted to acetyl CoA, yielding 8 ATP per glucose molecule via fermentation.
Correct answer
C. Glycolysis continues with NAD ^+ regeneration via lactate fermentation, yielding 2 ATP per glucose molecule.
Step-by-step solution
Pyruvate dehydrogenase is the enzyme responsible for the oxidative decarboxylation of pyruvate to form acetyl-CoA, which links glycolysis to the Krebs cycle. If this enzyme is completely inhibited, pyruvate cannot enter the Krebs cycle for further oxidation. To meet its energy demands, the cell must rely entirely on glycolysis. For glycolysis to continue, a steady supply of NAD ^+ is required. In the absence of the mitochondrial electron transport chain's ability to oxidize NADH (since the Krebs cycle is halted), t