Metabolism of one palmitic acid yields ATP

Options

A. 36 ATP
B. 56 ATP
C. 129 ATP
D. 48 ATP

Explanation

To determine the total ATP yield from the metabolism of one molecule of palmitic acid, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Structure of Palmitic Acid**:
- Palmitic acid is a saturated fatty acid with 16 carbon atoms (C16H32O2).

2. **Understand the Process of Beta-Oxidation**:
- Palmitic acid undergoes beta-oxidation, which breaks down the fatty acid into acetyl-CoA units.

3. **Calculate the Number of Acetyl-CoA Produced**:
- Each cycle of beta-oxidation removes 2 carbon atoms, producing one acetyl-CoA.
- For palmitic acid (16 carbons), it will produce 8 acetyl-CoA (16/2 = 8).

4. **Determine the Number of NADH and FADH2 Produced**:
- Beta-oxidation of palmitic acid involves 7 cycles (one less than the number of acetyl-CoA produced).
- Each cycle produces 1 NADH and 1 FADH2.
- Therefore, 7 NADH and 7 FADH2 are produced.

5. **Calculate ATP Yield from NADH and FADH2**:
- Each NADH yields 3 ATP.
- Each FADH2 yields 2 ATP.
- Total ATP from NADH: 7 NADH × 3 ATP/NADH = 21 ATP.
- Total ATP from FADH2: 7 FADH2 × 2 ATP/FADH2 = 14 ATP.

6. **Calculate ATP Yield from Acetyl-CoA**:
- Each acetyl-CoA yields 12 ATP in the Krebs cycle.
- Total ATP from 8 acetyl-CoA: 8 acetyl-CoA × 12 ATP/acetyl-CoA = 96 ATP.

7. **Add Up All ATP Yields**:
- Total ATP from NADH = 21 ATP.
- Total ATP from FADH2 = 14 ATP.
- Total ATP from acetyl-CoA = 96 ATP.
- Total ATP before considering activation: 21 + 14 + 96 = 131 ATP.

8. **Account for Activation Energy**:
- The activation of palmitic acid requires 2 ATP.
- Therefore, the total ATP yield after subtracting the activation cost: 131 ATP - 2 ATP = 129 ATP.

### Final Answer:
The metabolism of one palmitic acid yields **129 ATP**.

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