A portion of the antigen, the antigenic determinant, which can bind to the antigen binding site (paratope) of the antibody is

Options

A. opsonin
B. antigen-antibody complex
C. epitope
D. none of these

Answer

To answer the question regarding the portion of the antigen that binds to the antigen binding site (paratope) of the antibody, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Antigens and Antibodies**:
- Antigens are substances that can provoke an immune response, and antibodies are proteins produced by the immune system to identify and neutralize these antigens.

2. **Identifying Key Terms**:
- The term "antigenic determinant" refers to the specific part of the antigen that is recognized by the immune system, particularly by antibodies.
- The "paratope" is the specific region on the antibody that binds to the antigen.

3. **Defining the Binding Interaction**:
- The interaction between the antigen and the antibody occurs at specific sites. The paratope of the antibody binds to the antigenic determinant of the antigen.

4. **Naming the Binding Site**:
- The specific part of the antigen that the paratope binds to is called the "epitope." However, in the context of the video, the term "FV-tope" is used to refer to the binding site on the antibody where the paratope interacts with the epitope of the antigen.

5. **Evaluating Other Options**:
- The other options provided (opsonin and antigen-antibody complex) do not directly answer the question about the specific part of the antigen that binds to the antibody's paratope.

6. **Conclusion**:
- Based on the definitions and the context provided, the correct answer to the question is "FV-tope."

### Final Answer:
The portion of the antigen that can bind to the antigen binding site (paratope) of the antibody is called the **FV-tope**.

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