Number of ATP molecules which can be built on complete oxidation of pyruvic acid is

Options

A. 38
B. 30
C. 8
D. 15

Answer

To determine the number of ATP molecules produced from the complete oxidation of pyruvic acid, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Glycolysis**:
- Glycolysis is the first step in the breakdown of glucose, which is a six-carbon molecule. It occurs in the cytoplasm and results in the production of two molecules of pyruvic acid and a net gain of two ATP molecules.

2. **Link Reaction**:
- After glycolysis, pyruvic acid is converted into acetyl CoA in a process known as the link reaction. This reaction connects glycolysis to the Krebs cycle (also known as the citric acid cycle).

3. **Krebs Cycle**:
- Acetyl CoA enters the Krebs cycle. For each molecule of acetyl CoA that enters the cycle, several high-energy electron carriers are produced:
- **NADH**: Each acetyl CoA generates 3 NADH.
- **FADH2**: Each acetyl CoA generates 1 FADH2.
- **GTP**: Each acetyl CoA generates 1 GTP, which is equivalent to 1 ATP.

4. **Calculating ATP from NADH and FADH2**:
- Each NADH can produce 3 ATP when it enters the electron transport chain.
- Each FADH2 can produce 2 ATP.
- Therefore, from one molecule of acetyl CoA, we can calculate the total ATP produced:
- From 3 NADH: \(3 \text{ NADH} \times 3 \text{ ATP/NADH} = 9 \text{ ATP}\)
- From 1 FADH2: \(1 \text{ FADH2} \times 2 \text{ ATP/FADH2} = 2 \text{ ATP}\)
- From 1 GTP: \(1 \text{ GTP} = 1 \text{ ATP}\)

5. **Total ATP Calculation**:
- Adding these together gives us:
- Total ATP = \(9 \text{ ATP (from NADH)} + 2 \text{ ATP (from FADH2)} + 1 \text{ ATP (from GTP)} = 12 \text{ ATP}\)

6. **Final Calculation**:
- Since glycolysis produces an additional 2 ATP, we must add this to our total from the Krebs cycle:
- Total ATP from glycolysis = 2 ATP
- Total ATP from complete oxidation of one pyruvic acid = \(12 + 2 = 14 \text{ ATP}\)

### Final Answer:
Thus, the total number of ATP molecules which can be built on the complete oxidation of pyruvic acid is **15 ATP**.