ATP Yield from Glucose Oxidation vs. β-Oxidation of Palmitic Acid
ATP Production from Glucose Oxidation
Complete aerobic oxidation of one glucose molecule involves three main stages: glycolysis, the TCA cycle, and oxidative phosphorylation. Below is a breakdown of the ATP yield:
1. Glycolysis
- 2 ATP (net gain)
- 2 NADH → 5 ATP (via oxidative phosphorylation)
2. Pyruvate to Acetyl-CoA
- 2 NADH (from 2 pyruvate) → 5 ATP
3. TCA Cycle (2 Acetyl-CoA)
- 6 NADH → 15 ATP
- 2 FADH₂ → 3 ATP
- 2 GTP → 2 ATP
Total ATP Yield from One Glucose:
- Glycolysis: 7 ATP
- Pyruvate oxidation: 5 ATP
- TCA cycle: 20 ATP
- Total: 32 ATP
ATP Production from β-Oxidation of Palmitic Acid (C16:0)
Palmitic acid undergoes 7 cycles of β-oxidation, generating:
- 8 Acetyl-CoA → 80 ATP (8 × 10 via TCA cycle)
- 7 NADH → 17.5 ATP
- 7 FADH₂ → 10.5 ATP
- Total ATP = 108 ATP – 2 ATP (activation cost) = 106 ATP
Comparison
| Substrate | Total ATP Produced |
|---|---|
| Glucose (C6) | 32 ATP |
| Palmitic Acid (C16) | 106 ATP |
Conclusion
β-Oxidation of palmitic acid produces significantly more ATP than the complete oxidation of glucose. This illustrates why fatty acids are a more efficient long-term energy storage molecule in organisms.