Total number of ATP produced when one molecule of G3P, participates in aerobic respiration is

Options

A. 18
B. 14
C. 17
D. 16

Answer

To determine the total number of ATP produced when one molecule of G3P (glyceraldehyde 3-phosphate) participates in aerobic respiration, we need to analyze the steps involved in glycolysis and the Krebs cycle.

### Step-by-Step Solution:

1. **Understanding G3P**:
- G3P is an intermediate product of glycolysis. It can be converted into pyruvate, which then enters the Krebs cycle.

2. **Glycolysis**:
- In glycolysis, one molecule of G3P is converted to pyruvate. During this process:
- **2 ATP** are produced directly.
- **1 NADH** is generated (which can produce ATP in the electron transport chain).

3. **Conversion of Pyruvate to Acetyl CoA**:
- Each pyruvate produced from G3P is converted to Acetyl CoA, yielding **1 NADH** per pyruvate. Since we started with one G3P, we have:
- **1 NADH** from pyruvate to Acetyl CoA.

4. **Krebs Cycle**:
- Each Acetyl CoA enters the Krebs cycle. For each Acetyl CoA, the following ATP equivalents are produced:
- **3 NADH** (which can produce ATP in the electron transport chain).
- **1 FADH2** (which also contributes to ATP production).
- **1 GTP** (equivalent to 1 ATP).

5. **Total ATP Calculation**:
- From glycolysis (from G3P to pyruvate):
- 2 ATP (directly) + 1 NADH (2.5 ATP) = 2 + 2.5 = 4.5 ATP
- From the conversion of pyruvate to Acetyl CoA:
- 1 NADH = 2.5 ATP
- From the Krebs cycle (1 Acetyl CoA):
- 3 NADH = 3 x 2.5 ATP = 7.5 ATP
- 1 FADH2 = 1.5 ATP
- 1 GTP = 1 ATP
- Total from Krebs cycle = 7.5 + 1.5 + 1 = 10 ATP

6. **Final Total**:
- Adding everything together:
- Glycolysis: 4.5 ATP
- Pyruvate to Acetyl CoA: 2.5 ATP
- Krebs Cycle: 10 ATP
- Total ATP = 4.5 + 2.5 + 10 = **17 ATP**

### Conclusion:
The total number of ATP produced when one molecule of G3P participates in aerobic respiration is **17 ATP**.

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