Fluorescent dye bonded to monoclonal antibodies is used to locate particular

Options

A. Cell proteins
B. Cells
C. Diseased parts
D. Organs of defence.

Answer

### Step-by-Step Solution:

1. **Understanding Monoclonal Antibodies**:
- Monoclonal antibodies are antibodies that are made by identical immune cells that are all clones of a unique parent cell. They bind to specific antigens (foreign particles) in the body.

2. **Role of Antibodies**:
- Antibodies recognize and bind to antigens, which can be proteins on the surface of pathogens or diseased cells. This binding is crucial for the immune response.

3. **Fluorescent Dye**:
- A fluorescent dye is a substance that emits light when exposed to specific wavelengths of light (usually UV light). When attached to monoclonal antibodies, it helps visualize the location of the antibodies in biological samples.

4. **Application of Fluorescent Dye with Monoclonal Antibodies**:
- The combination of fluorescent dye and monoclonal antibodies allows researchers to locate specific proteins within cells. This is done through a process called immunofluorescence.

5. **Identifying the Target**:
- The question asks what the fluorescent dye bonded to monoclonal antibodies is used to locate. Based on the function of monoclonal antibodies and the application of fluorescent dyes, the correct answer is that they are used to locate **cell proteins**.

6. **Eliminating Incorrect Options**:
- The other options (cell, diseased part, organ of defense) do not accurately reflect the specific target that the fluorescent dye and monoclonal antibodies are used to identify.

7. **Final Answer**:
- Therefore, the correct answer is **cell proteins**.