Total number of ATP produced through ETS only from one molecule of 3-phosphoglycerate in aerobic respiration is

Options

A. 14
B. 12
C. 15
D. 16

Answer

To determine the total number of ATP produced through the electron transport system (ETS) from one molecule of 3-phosphoglycerate (3-PGA) in aerobic respiration, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Starting Point**:
- 3-phosphoglycerate (3-PGA) is produced during glycolysis from glucose.

2. **Conversion of 3-PGA to Pyruvate**:
- One molecule of 3-PGA is converted into one molecule of pyruvate. During this conversion, 1 NADH molecule is produced.

3. **Formation of Acetyl-CoA**:
- Each pyruvate molecule then undergoes decarboxylation to form acetyl-CoA. Since one molecule of 3-PGA produces one pyruvate, this results in the formation of 1 acetyl-CoA.

4. **Krebs Cycle Entry**:
- The acetyl-CoA enters the Krebs cycle. Each acetyl-CoA that enters the Krebs cycle produces:
- 3 NADH
- 1 FADH2

5. **Total NADH and FADH2 from One 3-PGA**:
- From the conversion of 3-PGA to pyruvate: 1 NADH
- From the Krebs cycle (1 acetyl-CoA): 3 NADH + 1 FADH2
- Therefore, the total is:
- NADH = 1 (from glycolysis) + 3 (from Krebs) = 4 NADH
- FADH2 = 1 (from Krebs)

6. **ATP Production from NADH and FADH2**:
- Each NADH produces approximately 3 ATP in the ETS.
- Each FADH2 produces approximately 2 ATP in the ETS.
- So, from 4 NADH: 4 NADH × 3 ATP/NADH = 12 ATP
- From 1 FADH2: 1 FADH2 × 2 ATP/FADH2 = 2 ATP

7. **Total ATP Calculation**:
- Total ATP from NADH = 12 ATP
- Total ATP from FADH2 = 2 ATP
- Grand total ATP = 12 + 2 = 14 ATP

### Final Answer:
The total number of ATP produced through the ETS from one molecule of 3-phosphoglycerate in aerobic respiration is **14 ATP**.

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