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 regarding where exonuclease cuts DNA, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Exonuclease**:
- Exonuclease is an enzyme that cleaves nucleotides one at a time from the end of a polynucleotide chain (DNA or RNA). The term "exo" means "outside," indicating that this enzyme works from the ends of the DNA molecule.

2. **Analyzing the Options**:
- **Option 1: Within the polynucleotide chain**: This option suggests that exonuclease cuts DNA internally. However, this is incorrect because exonucleases act from the ends, not the middle.
- **Option 2: At the end of the polynucleotide chain**: This option is correct. Exonucleases remove nucleotides from the ends of the DNA strand.
- **Option 3: At a particular site of polynucleotide**: This option refers to endonucleases, which cut DNA at specific internal sites. Therefore, this is incorrect for exonucleases.
- **Option 4: At the end of polypeptides**: Polypeptides are made of amino acids, not nucleotides. Nucleases do not act on polypeptides, making this option incorrect.

3. **Conclusion**:
- Based on the analysis of the options, the correct answer is **Option 2: At the end of the polynucleotide chain**.

### Final Answer:
The correct answer is **Option 2: At the end of the polynucleotide chain**.