Which one of the following types of reaction occurs when a peptide link in a protein is broken ?

Options

A. Condensation
B. Substitution
C. Addition
D. Hydrolysis

Answer

To determine which type of reaction occurs when a peptide link in a protein is broken, we need to analyze the nature of peptide bonds and the process involved in breaking them.

### Step-by-Step Solution:

1. **Understanding Peptide Bonds**:
- A peptide bond is formed between two amino acids through a condensation reaction, where a molecule of water is released. This occurs when the carboxyl group of one amino acid reacts with the amino group of another.

2. **Identifying the Reaction Type**:
- When we break a peptide bond, we need to consider the reverse of the condensation reaction. The breaking of a bond typically involves the addition of water.

3. **Hydrolysis Reaction**:
- The process of breaking down a peptide bond by adding water is called hydrolysis. In hydrolysis, water is used to cleave the bond, resulting in the formation of two separate amino acids from the peptide.

4. **Conclusion**:
- Therefore, the reaction that occurs when a peptide link in a protein is broken is **hydrolysis**.

### Final Answer:
The type of reaction that occurs when a peptide link in a protein is broken is **hydrolysis**.

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