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 are essential in molecular biology. They function by recognizing specific short sequences of nucleotides in DNA.

2. **Analyzing the Statements**:
- The question provides four statements regarding restriction enzymes, and we need to evaluate each one to determine which is correct.

3. **Evaluating Statement 1**:
- The first statement claims that restriction enzymes "recognize the specific sequence and cleave RNA at the specific sequence."
- This statement is incorrect because restriction enzymes primarily act on DNA, not RNA.

4. **Evaluating Statement 2**:
- The second statement states that restriction enzymes "do not recognize or cleave specific sequences."
- This statement is also incorrect, as restriction enzymes are defined by their ability to recognize and cleave specific DNA sequences.

5. **Evaluating Statement 3**:
- The third statement asserts that restriction enzymes "recognize specific sequence and cleave at specific sequence of DNA."
- This statement is correct. Restriction enzymes indeed recognize specific sequences of DNA and cleave them at those specific sites.

6. **Evaluating Statement 4**:
- The fourth statement claims that restriction enzymes "restrict growth of bacteria."
- This statement is incorrect. While some enzymes can have effects on bacterial growth, it is antibiotics that primarily restrict bacterial growth, not restriction enzymes.

7. **Conclusion**:
- After evaluating all the statements, the correct answer is the third statement, which accurately describes the function of restriction enzymes.

### Final Answer:
The correct statement about restriction enzymes is: **"Recognize specific sequence and cleave at specific sequence of DNA."**

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