Restriction endonucleases are enzymes which:

Options

A. Remove nucleotides from the ends to the DNA moleculs
B. Make cuts at specific positions within the DNA molecules
C. Recognize a specific nucleotide sequence for binding of DNA ligas
D. Restrict the action of the enzyme DNA polymerase

Answer

**Step-by-Step Solution:**

1. **Understand the Definition of Restriction Endonucleases:**
- Restriction endonucleases, also known as restriction enzymes, are proteins that cut DNA at specific sequences. They are essential tools in molecular biology and genetic engineering.

2. **Analyze the Options Given in the Question:**
- The options provided are:
a) Remove nucleotides from the ends of DNA molecules.
b) Make cuts at specific positions within DNA molecules.
c) Recognize specific nucleotide sequences for binding of DNA ligase.
d) Restrict the action of enzyme DNA polymerase.

3. **Evaluate Each Option:**
- **Option A:** "Remove nucleotides from the ends of DNA molecules."
- This is incorrect. Restriction endonucleases do not simply remove nucleotides from the ends; they cut DNA at specific sites.
- **Option B:** "Make cuts at specific positions within DNA molecules."
- This is correct. Restriction endonucleases cleave DNA at specific sequences known as restriction sites.
- **Option C:** "Recognize specific nucleotide sequences for binding of DNA ligase."
- This is incorrect. While restriction endonucleases recognize specific sequences, they do not bind DNA ligase.
- **Option D:** "Restrict the action of enzyme DNA polymerase."
- This is also incorrect. Restriction endonucleases do not restrict DNA polymerase; they function independently.

4. **Conclusion:**
- The correct answer is **Option B:** "Make cuts at specific positions within DNA molecules."