Number of polypeptide chains present in a molecule of antibody :

Options

A. 2
B. 4
C. 6
D. 8

Answer

To determine the number of polypeptide chains present in a molecule of antibody, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Antibodies**:
- Antibodies, also known as immunoglobulins, are glycoproteins that play a crucial role in the immune response by recognizing and binding to specific antigens.

2. **Identify the Components of Antibodies**:
- Each antibody molecule is made up of four polypeptide chains. These chains consist of two types: light chains and heavy chains.

3. **Count the Polypeptide Chains**:
- In total, an antibody has:
- 2 light chains
- 2 heavy chains
- Therefore, the total number of polypeptide chains in an antibody is 2 (light) + 2 (heavy) = 4 polypeptide chains.

4. **Evaluate the Options**:
- If we look at the options:
- Option A: 2 chains (Incorrect)
- Option B: 4 chains (Correct)
- Option C: 6 chains (Incorrect)
- Option D: 8 chains (Incorrect)

5. **Conclusion**:
- The correct answer is that there are 4 polypeptide chains present in a molecule of antibody.

### Final Answer:
The number of polypeptide chains present in a molecule of antibody is **4**.