During glycolysis , isomerization occurs in how many steps ?

Options

A. 2
B. 3
C. 4
D. 5

Answer

To determine how many steps of isomerization occur during glycolysis, we can analyze the glycolytic pathway and identify the specific steps where isomerization takes place.

### Step-by-Step Solution:

1. **Understanding Glycolysis**: Glycolysis is a metabolic pathway that converts glucose into pyruvate, producing ATP and NADH in the process. It consists of several steps, some of which involve isomerization.

2. **Identifying Isomerization Steps**: Isomerization refers to the rearrangement of atoms within a molecule, resulting in a change in structure but not in molecular formula. In glycolysis, we need to identify the steps where this occurs.

3. **Step 1 - Glucose-6-Phosphate to Fructose-6-Phosphate**: The first isomerization occurs when glucose-6-phosphate is converted to fructose-6-phosphate. This reaction is catalyzed by the enzyme phosphoglucose isomerase.

4. **Step 2 - Dihydroxyacetone Phosphate to Glyceraldehyde-3-Phosphate**: The second isomerization occurs when dihydroxyacetone phosphate (DHAP) is converted to glyceraldehyde-3-phosphate (G3P). This is catalyzed by the enzyme triose phosphate isomerase.

5. **Step 3 - 3-Phosphoglycerate to 2-Phosphoglycerate**: The third isomerization occurs when 3-phosphoglycerate is converted to 2-phosphoglycerate, catalyzed by the enzyme phosphoglycerate mutase.

6. **Conclusion**: After analyzing the glycolytic pathway, we find that isomerization occurs in three distinct steps.

### Final Answer:
Isomerization occurs in **3 steps** during glycolysis.