which of the following is not the application of PCR ?

Options

A. Detection of very low concentration of bacteria or virus
B. Detection of mutations in genes in suspected cancer patients
C. Amplification of desired DNA segment
D. Detection of antibodies synthesised against pathogens

Answer

To determine which of the following is not an application of PCR (Polymerase Chain Reaction), we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding PCR**:
- PCR is a technique used to amplify small segments of DNA, creating millions of copies of a specific DNA sequence. This is crucial for various applications in molecular biology, genetics, and forensic science.

2. **Reviewing the Options**:
- **Option A**: Detection of very low concentration of bacteria or virus.
- **Analysis**: This is a common application of PCR. By amplifying the DNA of the bacteria or virus, PCR can detect very low concentrations that would otherwise be undetectable.

- **Option B**: Detection of germ mutations in genes in suspected cancer patients.
- **Analysis**: This is also a valid application. PCR can amplify specific regions of DNA where mutations may occur, allowing for their detection in cancer diagnostics.

- **Option C**: Amplification of desired DNA segments.
- **Analysis**: This is essentially the primary function of PCR itself. It is not just an application but the fundamental purpose of the technique.

- **Option D**: Detection of antibodies synthesized against pathogens.
- **Analysis**: This is not an application of PCR. Antibodies are proteins produced in response to antigens, and their detection typically involves methods like ELISA (Enzyme-Linked Immunosorbent Assay), which do not require DNA amplification.

3. **Conclusion**:
- The option that is not an application of PCR is **Option D: Detection of antibodies synthesized against pathogens**.

### Final Answer:
**Option D** is not an application of PCR.

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