The four polypetide chains of the antibody molecules are held together by:-

Options

A. Peptide bonds
B. Disulphide bonds
C. Ionic bonds
D. Vander waal's interactions

Answer

To answer the question about how the four polypeptide chains of antibody molecules are held together, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Antibody Structure**:
- Antibodies are proteins made up of four polypeptide chains: two heavy chains and two light chains. These chains are essential for the antibody's function in the immune response.

2. **Identifying the Bonds in Proteins**:
- Proteins are formed by amino acids linked together by peptide bonds. However, in the context of the overall structure of antibodies, we need to consider how these polypeptide chains are held together.

3. **Recognizing the Role of Disulfide Bonds**:
- The polypeptide chains in antibodies are stabilized by disulfide bonds. These bonds form between the sulfur atoms of cysteine residues in the polypeptide chains.

4. **Evaluating Other Bond Types**:
- Other types of bonds, such as ionic bonds and van der Waals interactions, play roles in protein structure but are not the primary bonds holding the polypeptide chains of antibodies together.

5. **Conclusion**:
- The correct answer to the question is that the four polypeptide chains of the antibody molecules are held together by disulfide bonds.

### Final Answer:
The four polypeptide chains of the antibody molecules are held together by **disulfide bonds**.

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