Which of the following is produced by the complete oxidation one molecule of palmitic acid in mitochondrial beta oxidation?
## **Core Concept**
The complete oxidation of fatty acids, such as palmitic acid, occurs through a series of steps known as beta-oxidation, which takes place in the mitochondria. This process involves the sequential removal of two-carbon units from the carboxyl end of the fatty acid chain, resulting in the production of acetyl-CoA. The acetyl-CoA can then enter the citric acid cycle (Krebs cycle) for further oxidation.
## **Why the Correct Answer is Right**
Palmitic acid is a 16-carbon saturated fatty acid. During beta-oxidation, it undergoes seven cycles of oxidation, each cycle producing one NADH, one FADH2, and one acetyl-CoA. Since palmitic acid is converted into eight acetyl-CoA molecules (16 carbons / 2 carbons per acetyl-CoA), and each acetyl-CoA can produce 10 ATPs (through the citric acid cycle and oxidative phosphorylation), the complete oxidation of palmitic acid yields a significant amount of ATP. The correct answer, , indicates that 106 ATP molecules are produced from the complete oxidation of one molecule of palmitic acid. This calculation comes from:
- 7 cycles of beta-oxidation producing 7 NADH and 7 FADH2.
- 8 acetyl-CoA molecules entering the citric acid cycle, producing 8 * 10 = 80 ATP (considering 10 ATP per acetyl-CoA, which includes the citric acid cycle, oxidative phosphorylation, but not the initial steps of beta-oxidation).
- The direct ATP yield from beta-oxidation: 7 NADH * 2.5 ATP = 17.5 ATP, and 7 FADH2 * 1.5 ATP = 10.5 ATP.
## **Why Each Wrong Option is Incorrect**
- **Option A:** . This option underestimates the ATP yield. The complete oxidation of palmitic acid indeed produces more than 50 ATP molecules.
- **Option B:** . This is still an underestimation. While it's closer, it doesn't accurately reflect the complete oxidation products.
- **Option C:** . This option overestimates. The actual ATP yield from palmitic acid oxidation is not 120.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the oxidation of fatty acids is a crucial energy-producing pathway, especially during fasting periods or when glucose levels are low. Beta-oxidation defects can lead to serious metabolic disorders, highlighting the importance of this pathway in human metabolism.
## **Correct Answer:** .