The cutting of DNA by restriction endonucleases results in fragments of DNA. These fragments are generally separated by a technique known as

Options

A. Gel- filtration chromatography
B. Centrifugation
C. Gel electrophoresis
D. Thin-layer chromatography

Answer

To solve the question regarding the technique used to separate DNA fragments produced by the cutting of DNA by restriction endonucleases, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Restriction Endonucleases**:
- Restriction endonucleases are enzymes that cut DNA at specific sequences, resulting in fragments of varying lengths.
- These fragments are the focus of separation techniques.

2. **Identifying Separation Techniques**:
- The options provided are:
- Gel filtration chromatography
- Centrifugation
- Gel electrophoresis
- Thin layer chromatography

3. **Analyzing Each Option**:
- **Gel Filtration Chromatography**:
- This technique separates molecules based on size but is generally used for proteins and larger molecules, not specifically for DNA fragments.
- **Centrifugation**:
- This method separates substances based on density and is not suitable for separating DNA fragments specifically.
- **Thin Layer Chromatography**:
- This technique is used for separating small molecules and is not typically used for DNA fragment separation.
- **Gel Electrophoresis**:
- This is a widely used method in molecular biology for separating DNA fragments based on size. When an electric current is applied, negatively charged DNA fragments move towards the positive electrode, allowing for size-based separation.

4. **Conclusion**:
- Given the analysis, the most appropriate technique for separating DNA fragments produced by restriction endonucleases is **gel electrophoresis**.

### Final Answer:
The fragments of DNA are generally separated by a technique known as **gel electrophoresis**.

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