Question

Total number of ATP molecules formed (net gain) during the process of aerobic respiration is

• A. 42
• B. 14
• C. 30
• D. 36

Answer 1

The correct option is D 36

• Aerobic respiration occurs in four stages:-

1) Glycolysis (gain of 2 ATP & 2 NADH molecules)

2) formation of Acetyl Coenzyme A from pyruvate (gain of 2 NADH molecules)

3) The citric acid cycle (gain of 6 NADH, 2 FADH, and 2 GTP molecules)

4) Electron transport chain and oxidative phosphorylation

• During oxidative phosphorylation, every NADH molecule can yield 3 ATP while the FADH molecule yields 2 ATP.
• So in total, there are 10 NADH (3 X 10 = 30 ATP) +2 FADH (2 X 2 = 4 ATP) + 4 ATP (GTP is equivalent to ATP) = 38 ATP.
• But in most eukaryotic cells, 2 molecules of ATP are required for transporting the NADH produced in glycolysis into the mitochondrion for further oxidative phosphorylation. Hence, the net gain of ATP is 36 molecules.
  

So, the correct answer is option D.