Which antibody molecule is made of two monomers ?

Options

A. IgM
B. IgG
C. IgA
D. IgE

Answer

To answer the question "Which antibody molecule is made of two monomers?" we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Antibodies**:
- Antibodies, also known as immunoglobulins, are proteins produced by the immune system to identify and neutralize foreign objects like bacteria and viruses.

2. **Types of Antibodies**:
- There are five main types of antibodies in humans: IgG, IgM, IgD, IgA, and IgE. Each type has a unique structure and function.

3. **Analyzing Each Antibody Type**:
- **IgG**: This is a monomer, meaning it consists of a single unit.
- **IgM**: This antibody is a pentamer, made up of five monomers.
- **IgD**: This is also a monomer.
- **IgE**: This antibody is a monomer as well.
- **IgA**: This antibody is a dimer, meaning it is composed of two monomers.

4. **Identifying the Correct Answer**:
- Since we are looking for an antibody made of two monomers, the correct answer is **IgA**, as it is specifically known to exist in a dimeric form.

5. **Conclusion**:
- Therefore, the antibody molecule that is made of two monomers is **IgA**.

### Final Answer:
**IgA**