Conversion of substrate to products is associated with change in the structure but not in the molecular weight is

Options

A. Isomerisation
B. Oxidation
C. Cleavage reaction
D. Phosphorylation

Answer

To solve the question regarding the conversion of a substrate to products that involves a change in structure but not in molecular weight, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question is asking for a type of reaction where the substrate is converted into products with a change in structure but no change in molecular weight. This means that the number of atoms and their types remain the same, but their arrangement changes.

2. **Identify the Options**: The options provided are:
- Isomerization
- Oxidation
- Cleavage reaction
- Phosphorylation

3. **Analyze Each Option**:
- **Isomerization**: This reaction involves the rearrangement of atoms within a molecule, resulting in a different isomer. Importantly, the molecular weight remains the same because no atoms are added or removed.
- **Oxidation**: This reaction typically involves the loss of electrons or the addition of oxygen, which usually changes the molecular weight because it can involve the addition or removal of atoms.
- **Cleavage Reaction**: This involves breaking a molecule into smaller parts, which would change the molecular weight as the original molecule is split into two or more products.
- **Phosphorylation**: This reaction involves the addition of a phosphate group to a molecule, which increases the molecular weight.

4. **Conclusion**: Based on the analysis, the only reaction that fits the criteria of changing structure without changing molecular weight is **Isomerization**. In isomerization, the substrate is transformed into a different isomer, maintaining the same molecular formula.

5. **Final Answer**: The correct answer is **Isomerization**.