The net production of NADH molecules when 4 glucose molecules yeild 8 molecules of lactic acid through glycolysis and subsequenet fermantation is

Options

A. Four
B. Eight
C. Zero
D. Two.

Answer

To determine the net production of NADH molecules when 4 glucose molecules yield 8 molecules of lactic acid through glycolysis and subsequent fermentation, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Glycolysis**:
- Glycolysis is the first step in the breakdown of glucose. For each glucose molecule, glycolysis produces 2 pyruvate molecules and 2 NADH molecules.
- Therefore, for 4 glucose molecules, the total production from glycolysis would be:
\[ 4 \text{ glucose} \times 2 \text{ NADH/glucose} = 8 \text{ NADH} \]

2. **Fermentation Process**:
- In anaerobic conditions (like fermentation), the pyruvate produced from glycolysis is converted into lactic acid.
- During this process, the 2 NADH produced from glycolysis are used to convert pyruvate into lactic acid, which also regenerates NAD+.
- This means that the 8 NADH produced during glycolysis are recycled back to NAD+ during the fermentation process.

3. **Net Production of NADH**:
- Since the NADH produced in glycolysis is used up in fermentation to regenerate NAD+, there is no net gain of NADH.
- Therefore, the net production of NADH when 4 glucose molecules yield 8 lactic acid molecules is:
\[ \text{Net NADH} = 8 \text{ NADH (produced)} - 8 \text{ NADH (used)} = 0 \]

### Conclusion:
The net production of NADH molecules when 4 glucose molecules yield 8 molecules of lactic acid is **0**.