Complete Metabolism of Glucose
The complete metabolism of glucose through cellular respiration involves several stages: Glycolysis, the Krebs cycle, and the Electron Transport Chain (ETC). Here’s a breakdown of ATP production in each stage.
1. Glycolysis
- Occurs in the cytoplasm.
- Converts one glucose molecule into two molecules of pyruvate.
- Produces:
- 2 ATP (net gain).
- 2 NADH (which can yield additional ATP during oxidative phosphorylation).
2. Pyruvate Decarboxylation
- Pyruvate enters the mitochondria and is converted to Acetyl-CoA.
- Produces:
- 2 NADH (one from each pyruvate).
3. Krebs Cycle (Citric Acid Cycle)
- Takes place in the mitochondrial matrix.
- Each Acetyl-CoA enters the cycle, producing:
- 2 ATP (1 ATP per cycle, and two cycles per glucose).
- 6 NADH (3 per cycle).
- 2 FADH2 (1 per cycle).
4. Electron Transport Chain (ETC)
- Located in the inner mitochondrial membrane.
- NADH produces approximately 2.5 ATP each, and FADH2 produces about 1.5 ATP each.
- From the previous stages:
- 10 NADH = 10 x 2.5 = 25 ATP.
- 2 FADH2 = 2 x 1.5 = 3 ATP.
Total ATP Calculation
- Glycolysis: 2 ATP + 2 NADH (5 ATP).
- Pyruvate Decarboxylation: 2 NADH (5 ATP).
- Krebs Cycle: 2 ATP + 6 NADH (15 ATP) + 2 FADH2 (3 ATP).
- Total: 2 + 5 + 5 + 2 + 15 + 3 = 32 ATP.
However, due to the use of ATP for transport and other processes, the net yield is typically rounded to about 30-36 ATP, commonly cited as 36 ATP for simplicity.
Conclusion
Thus, the correct answer is option 'C', with 36 ATP being formed during the complete metabolism of one glucose molecule.