Question

The net production of NADH molecules when 4 glucose molecules yield 8 molecules of lactic acid through glycolysis and subsequent fermentation is

• A. Four
• B. Eight
• C. Zero
• D. Two

Answer 1

Answer: (C)

Zero

In the process of glycolysis, a net profit of 2 ATP is gained from 1 glucose molecule along with 2 pyruvate molecules, and 2 NAD${}^{+}$ molecules are reduced to 2 NADH molecules as evident from the above figure. The 2 NADH molecules here are recycled back to NAD${}^{+}$ during the fermentation reaction where the 2 pyruvate molecules are reduced to 2 molecules of lactic acid. Glycolysis of 4 glucose molecules yield 8 pyruvate moleculs along with 8 NADH molecules. The 8 NADH molecules from glycolysis are now recycled to 8 NAD${}^{+}$ molecules to reduce the 8 pyruvate molecules into 8 molecules of lactic acid. So the net production of NADH molecules here is zero.