How many NAD molecules get reduced in complete oxidation of one glucose molecule

Options

A. 2
B. 5
C. 10
D. 12

Answer

To determine how many NAD molecules get reduced in the complete oxidation of one glucose molecule, we can break down the process of cellular respiration into its main stages: glycolysis, the conversion of pyruvate to acetyl-CoA, and the Krebs cycle (also known as the citric acid cycle).

### Step-by-Step Solution:

1. **Glycolysis**:
- In glycolysis, one glucose molecule is broken down into two molecules of pyruvate. During this process, 2 NAD molecules are reduced to form 2 NADH molecules.
- **NADH produced in glycolysis**: 2 NADH

2. **Conversion of Pyruvate to Acetyl-CoA**:
- Each pyruvate molecule is converted into acetyl-CoA. Since one glucose molecule produces two pyruvate molecules, this conversion occurs twice. For each conversion, 1 NAD molecule is reduced to form 1 NADH.
- **NADH produced during conversion**: 2 NADH (1 for each pyruvate)

3. **Krebs Cycle**:
- Each acetyl-CoA enters the Krebs cycle. For each turn of the cycle (which happens for each acetyl-CoA), 3 NAD molecules are reduced to form 3 NADH. Since there are 2 acetyl-CoA molecules produced from one glucose molecule, the Krebs cycle turns twice.
- **NADH produced in Krebs cycle**: 6 NADH (3 NADH per cycle × 2 cycles)

4. **Total NADH Production**:
- Now, we can sum up all the NADH produced from each stage:
- Glycolysis: 2 NADH
- Conversion of Pyruvate to Acetyl-CoA: 2 NADH
- Krebs Cycle: 6 NADH
- **Total NADH** = 2 + 2 + 6 = 10 NADH

Thus, the total number of NAD molecules that get reduced in the complete oxidation of one glucose molecule is **10 NADH**.

### Final Answer:
**10 NADH molecules are produced in the complete oxidation of one glucose molecule.**

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