Identify the reaction or step in EMP pathway which involves substrate level phosphorylation

Options

A. 1, 3-bisphosphoglyceric acid rarr 3 phosphoglyceric acid
B. Glyceraldehyde 3-phosphate rarr 1. 3-bisphosphoglyceric acid
C. Phosphoenolpyruvate rarr phosphoglycerate
D. Fructose-6-phosphate rarr Fructose-1, 6-bisphosphate

Answer

To identify the reaction or step in the EMP (Embden-Meyerhof-Parnas) pathway that involves substrate-level phosphorylation, we need to analyze the given options and understand the concept of substrate-level phosphorylation.

### Step-by-Step Solution:

1. **Understanding Substrate-Level Phosphorylation**:
- Substrate-level phosphorylation is a process where a phosphate group is directly transferred from a substrate to ADP to form ATP. This occurs during specific reactions in metabolic pathways, including glycolysis.

2. **Reviewing the Options**:
- We have four options to evaluate:
1. 1,3-bisphosphoglyceric acid to 3-phosphoglyceric acid
2. Glyceraldehyde 3-phosphate to 1,3-bisphosphoglyceric acid
3. Phosphoenolpyruvate to phosphoglycerate
4. Fructose 6-phosphate to fructose 1,6-bisphosphate

3. **Analyzing Each Option**:
- **Option 1**: **1,3-bisphosphoglyceric acid to 3-phosphoglyceric acid**:
- This reaction involves the transfer of a phosphate group from 1,3-bisphosphoglyceric acid to ADP, resulting in the formation of ATP. This is a classic example of substrate-level phosphorylation.
- **Option 2**: **Glyceraldehyde 3-phosphate to 1,3-bisphosphoglyceric acid**:
- In this step, NAD+ is reduced to NADH, and no ATP is produced. Therefore, this does not involve substrate-level phosphorylation.
- **Option 3**: **Phosphoenolpyruvate to phosphoglycerate**:
- This step does not involve the formation of ATP; rather, it is a conversion step without substrate-level phosphorylation.
- **Option 4**: **Fructose 6-phosphate to fructose 1,6-bisphosphate**:
- This reaction consumes ATP (it is a phosphorylation step), so it does not involve substrate-level phosphorylation.

4. **Conclusion**:
- The only reaction that involves substrate-level phosphorylation is **Option 1: 1,3-bisphosphoglyceric acid to 3-phosphoglyceric acid**.

### Final Answer:
The reaction in the EMP pathway that involves substrate-level phosphorylation is **1,3-bisphosphoglyceric acid to 3-phosphoglyceric acid**.