During rDNA technology, which one of the following enzymes is used for cleaving DNA molecule?

Options

A. Exonuclease
B. Endonuclease
C. Restriction endonuclease
D. Helicase

Answer

To solve the question regarding which enzyme is used for cleaving DNA molecules during recombinant DNA (rDNA) technology, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Context of rDNA Technology**:
- rDNA technology involves combining DNA from different sources to create new genetic combinations. This process requires specific enzymes to manipulate the DNA.

2. **Identify the Enzymes Listed in the Options**:
- The options provided are:
- a) Exonuclease
- b) Endonuclease
- c) Restriction Endonuclease
- d) Helicase

3. **Analyze Each Enzyme's Function**:
- **Exonuclease**: This enzyme removes nucleotides from the ends of a DNA molecule. It does not cleave DNA in the middle of a strand.
- **Endonuclease**: This enzyme cleaves the phosphodiester bonds within a polynucleotide chain, but it is a broader category and not specific to rDNA technology.
- **Restriction Endonuclease**: Also known as molecular scissors, these enzymes cut DNA at specific recognition sites. They are crucial for rDNA technology as they allow for precise cutting of DNA fragments.
- **Helicase**: This enzyme unwinds the DNA double helix but does not cleave DNA.

4. **Determine the Correct Answer**:
- Among the options, **Restriction Endonuclease** is the enzyme specifically used for cleaving DNA molecules in rDNA technology. It is designed to cut DNA at specific sequences, making it essential for the creation of recombinant DNA.

5. **Conclusion**:
- The correct answer is **c) Restriction Endonuclease**.