In the context of cellular respiration, what is the average number of ATP molecules produced from the complete aerobic oxidation of one molecule of glucose?

• A. 36-38 ATP
• B. 12 ATP
• C. 100 ATP
• D. 2 ATP

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by understanding the process of cellular respiration, which includes glycolysis, the citric acid cycle (Krebs cycle), and oxidative phosphorylation. These stages work together to convert glucose into ATP, the energy currency of the cell.
2. Step 2: Recall that glycolysis occurs in the cytoplasm and breaks down one molecule of glucose into two molecules of pyruvate, producing a net gain of 2 ATP and 2 NADH molecules.
3. Step 3: Next, the pyruvate molecules are transported into the mitochondria, where they are converted into acetyl-CoA. This step produces 2 NADH molecules (1 per pyruvate). Acetyl-CoA then enters the citric acid cycle, generating 2 ATP, 6 NADH, and 2 FADH₂ per glucose molecule.
4. Step 4: In oxidative phosphorylation, the NADH and FADH₂ molecules produced in earlier steps are used to drive the electron transport chain. Each NADH contributes to the production of approximately 2.5 ATP, and each FADH₂ contributes about 1.5 ATP. Calculate the total ATP yield by summing the contributions from glycolysis, the citric acid cycle, and oxidative phosphorylation.
5. Step 5: Account for variability in ATP yield due to differences in shuttle systems used to transport NADH from glycolysis into the mitochondria. This variability explains why the total ATP yield from one molecule of glucose is typically reported as 36-38 ATP.