In which of the following region , exonuclease will cute the DNA ?

Options

A. Within the Polynucleotide chain.
B. At end of the polynucleotide chain
C. At particular recognition sites on Polynucleotide.
D. At end of the polypeptide chain.

Answer

To solve the question "In which of the following regions will exonuclease cut the DNA?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Function of Exonuclease**:
- Exonucleases are enzymes that remove nucleotide monophosphates from the ends of a polynucleotide chain. They work specifically at the ends of the DNA strands.

2. **Identify the Options**:
- a. Within the polynucleotide chain
- b. At the end of the polynucleotide chain
- c. At particular recognition sites on polynucleotide
- d. At the end of the polynucleotide chain (Note: This option is repeated)

3. **Analyze Each Option**:
- **Option a**: "Within the polynucleotide chain" - This is incorrect because exonucleases do not cut DNA internally; that is the function of endonucleases.
- **Option b**: "At the end of the polynucleotide chain" - This is correct as exonucleases act at the ends of the DNA.
- **Option c**: "At particular recognition sites on polynucleotide" - This is incorrect for exonucleases; endonucleases may act at specific recognition sites.
- **Option d**: "At the end of the polynucleotide chain" - This is a repeat of option b and is also correct.

4. **Conclusion**:
- The correct answer is **b. At the end of the polynucleotide chain**.

### Final Answer:
- The exonuclease will cut the DNA at the end of the polynucleotide chain (Option b).