For two molecules of glucose, glycolysis uses and produces ATP molecules

Options

A. 4 and 8
B. 2 and 4
C. 2 and 8
D. 2 and 2

Answer

To solve the question regarding the ATP usage and production during glycolysis for two molecules of glucose, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Glycolysis:**
Glycolysis is the metabolic pathway that converts glucose into pyruvate, generating small amounts of ATP and NADH in the process.

2. **ATP Usage in Glycolysis:**
- For one molecule of glucose, glycolysis uses 2 ATP molecules in the initial steps.
- Specifically, one ATP is used to convert glucose to glucose-6-phosphate and another ATP is used to convert fructose-6-phosphate to fructose-1,6-bisphosphate.
- Therefore, for 2 molecules of glucose, the total ATP used is:
\[ 2 \text{ ATP (for 1 glucose)} \times 2 \text{ (for 2 glucose)} = 4 \text{ ATP} \]

3. **ATP Production in Glycolysis:**
- Glycolysis produces ATP through substrate-level phosphorylation.
- In the conversion of 2 molecules of glyceraldehyde-3-phosphate (from the split of fructose-1,6-bisphosphate), 2 ATP are produced (1 ATP per molecule).
- In the conversion of 2 molecules of phosphoenolpyruvate (PEP) to pyruvate, another 2 ATP are produced (1 ATP per molecule).
- Therefore, for 2 glucose molecules, the total ATP produced is:
\[ 4 \text{ ATP (from glyceraldehyde-3-phosphate)} + 4 \text{ ATP (from PEP)} = 8 \text{ ATP} \]

4. **Final Summary:**
- For two molecules of glucose, glycolysis uses 4 ATP and produces 8 ATP.

### Answer:
- **ATP Used:** 4
- **ATP Produced:** 8