Restriction enzyme :

Options

A. recognise the specific sequence and cleave RNA at the specific sequence
B. do not recognise or cleave the specific sequence
C. recognise specific sequence and cleave at specific sequence of DNA
D. restrict growth of bacteria

Answer

### Step-by-Step Solution:

1. **Understanding Restriction Enzymes**:
- Restriction enzymes, also known as restriction endonucleases, are proteins that cut DNA at specific sequences. The term "endonuclease" indicates that these enzymes cut within the DNA molecule (as opposed to exonucleases, which cut at the ends).

2. **Function of Restriction Enzymes**:
- These enzymes recognize specific nucleotide sequences in the DNA and cleave the DNA at or near these sites. This is crucial for various biotechnological applications, such as cloning and DNA manipulation.

3. **Analyzing the Options**:
- **Option 1**: "Recognize the specific sequence and cleave RNA at the specific sequence."
- This is incorrect because restriction enzymes primarily act on DNA, not RNA.
- **Option 2**: "Do not recognize or cleave the specific sequence."
- This is incorrect because the very definition of restriction enzymes is that they do recognize and cleave specific sequences.
- **Option 3**: "Recognize specific sequence and cleave at specific sequence of DNA."
- This is correct as it accurately describes the function of restriction enzymes.
- **Option 4**: "Restrict growth of bacteria."
- This is misleading; while some restriction enzymes are involved in bacterial defense mechanisms, their primary function is not to restrict bacterial growth.

4. **Conclusion**:
- The correct answer is **Option 3**: "Recognize specific sequence and cleave at specific sequence of DNA."