The enzyme restriction endonuclease …

Options

A. cuts double strand of DNA
B. joins strand of DNA
C. cuts RNA strand
D. cuts single stranded DNA

Answer

**Step-by-Step Solution:**

1. **Understanding Restriction Endonucleases**:
- Restriction endonucleases are enzymes that cut DNA at specific sequences. They are often referred to as molecular scissors due to their ability to cleave the DNA strands.

2. **Functionality of Restriction Endonucleases**:
- These enzymes function by recognizing specific nucleotide sequences within the double-stranded DNA. Each restriction enzyme has a unique recognition sequence where it will cut the DNA.

3. **Identifying the Correct Function**:
- The question presents several options regarding the actions of restriction endonucleases:
- Cuts double strand of DNA
- Joins strands of DNA
- Cuts RNA strand
- Cuts single strand of DNA

4. **Analyzing Each Option**:
- **Cuts double strand of DNA**: This is true; restriction endonucleases do cut double-stranded DNA at specific sites.
- **Joins strands of DNA**: This is false; joining DNA strands is the function of ligase enzymes, not restriction endonucleases.
- **Cuts RNA strand**: This is false; restriction endonucleases do not act on RNA.
- **Cuts single strand of DNA**: This is false; they specifically target double-stranded DNA.

5. **Conclusion**:
- Based on the analysis, the correct answer is that restriction endonucleases cut double-stranded DNA.

**Final Answer**: The enzyme restriction endonuclease cuts double strands of DNA.

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