Restriction endonucleases are used in genetic engineering to form

Options

A. Recombinant molecule of protein
B. Recombinant molecule of DNA
C. Recombinant molecule of protein & DNA
D. Recombinant cell

Answer

### Step-by-Step Solution:

1. **Understanding Restriction Endonucleases**:
- Restriction endonucleases are enzymes that cut DNA at specific sequences known as restriction sites. They are crucial tools in genetic engineering.

2. **Function of Restriction Endonucleases**:
- These enzymes act as molecular scissors, cleaving the DNA into smaller fragments. This ability allows scientists to manipulate DNA for various applications, including cloning and recombinant DNA technology.

3. **Formation of Recombinant DNA**:
- After cutting the DNA, the resulting fragments can be ligated (joined) to other DNA fragments that have also been cut by the same or compatible restriction endonucleases. This process leads to the formation of recombinant DNA molecules.

4. **Analyzing the Options**:
- **Recombinant molecule of protein**: Incorrect, as restriction endonucleases do not cut proteins.
- **Recombinant molecule of DNA**: Correct, as they are specifically used to create recombinant DNA.
- **Recombinant molecule of protein and DNA**: Incorrect, as they do not directly interact with proteins.
- **Recombinant cell**: Incorrect, as they do not cut whole cells but rather the DNA within them.

5. **Conclusion**:
- The correct answer is **recombinant molecule of DNA**.