The number of ATP molecules produced by electron transport system from Krebs cycle intermediates in a single turn is

Options

A. 11
B. 14
C. 12
D. 16

Answer

To determine the number of ATP molecules produced by the electron transport system from Krebs cycle intermediates in a single turn, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Intermediates Produced in the Krebs Cycle:**
- In one turn of the Krebs cycle, the following intermediates are produced:
- 3 NADH
- 1 FADH2
- 1 GTP

2. **Understand the Conversion of Intermediates to ATP:**
- Each NADH molecule produces 3 ATP when oxidized.
- Each FADH2 molecule produces 2 ATP when oxidized.
- GTP is equivalent to 1 ATP.

3. **Calculate ATP from NADH:**
- Since there are 3 NADH produced:
- ATP from NADH = 3 NADH × 3 ATP/NADH = 9 ATP

4. **Calculate ATP from FADH2:**
- There is 1 FADH2 produced:
- ATP from FADH2 = 1 FADH2 × 2 ATP/FADH2 = 2 ATP

5. **Account for GTP:**
- GTP produced is equivalent to 1 ATP:
- ATP from GTP = 1 ATP

6. **Total ATP Calculation:**
- Now, add all the ATP produced:
- Total ATP = ATP from NADH + ATP from FADH2 + ATP from GTP
- Total ATP = 9 ATP + 2 ATP + 1 ATP = 12 ATP

### Final Answer:
The number of ATP molecules produced by the electron transport system from Krebs cycle intermediates in a single turn is **12 ATP**.

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