Which step is not correct in DNA finger printing-

Options

A. Isolation of DNA
B. Digestion of DNA by DNA ligase enzyme
C. Separatio of DNA by electophoresis
D. Hybridisation using labelled VNTR probe

Answer

To determine which step is not correct in DNA fingerprinting, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Identify the Steps in DNA Fingerprinting**:
- The steps typically involved in DNA fingerprinting include:
1. Isolation of DNA
2. Digestion of DNA
3. Separation of DNA by electrophoresis
4. Hybridization using labeled VNTR probe
5. Analysis of the results (autoradiogram)

2. **Evaluate Each Option**:
- **Option 1: Isolation of DNA** - This is a necessary step in DNA fingerprinting as it involves obtaining DNA from the sample. **(Correct Step)**
- **Option 2: Digestion of DNA by DNA ligase enzyme** - DNA ligase is not used in DNA fingerprinting. Instead, restriction enzymes are typically used to cut the DNA at specific sites. Therefore, this step is not correct. **(Incorrect Step)**
- **Option 3: Separation of DNA by electrophoresis** - Gel electrophoresis is a crucial step in DNA fingerprinting, allowing for the separation of DNA fragments based on size. **(Correct Step)**
- **Option 4: Hybridization using labeled VNTR probe** - VNTR (Variable Number Tandem Repeats) probes are indeed used in the hybridization step of DNA fingerprinting to identify specific DNA sequences. **(Correct Step)**

3. **Conclusion**:
- The step that is not correct in DNA fingerprinting is **"Digestion of DNA by DNA ligase enzyme."** This is the only option that does not align with the standard procedures of DNA fingerprinting.

### Final Answer:
The step that is not correct in DNA fingerprinting is **"Digestion of DNA by DNA ligase enzyme."**

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