The nucleases Cleaving nucleotides one at a time from the end of the Polynucleotide chain are :

Options

A. Specific for '5' end of RNA stand
B. Specific for '3' end of RNA stand
C. Specific for both '5' and '3' ends of nucleotides strands
D. Non-Specific for both '5' and '3' ends of nucleotides strands

Answer

To solve the question, we need to identify the type of nucleases that cleave nucleotides one at a time from the ends of a polynucleotide chain. Let's break down the solution step by step.

### Step-by-Step Solution:

1. **Understanding Nucleases**:
- Nucleases are enzymes that cleave the bonds between nucleotides in nucleic acids (DNA or RNA).
- There are two main types of nucleases: **endonucleases** and **exonucleases**.

2. **Differentiating Between Endonucleases and Exonucleases**:
- **Endonucleases**: These enzymes cleave the phosphodiester bonds within the polynucleotide chain, meaning they cut the nucleic acid at specific internal sites rather than at the ends.
- **Exonucleases**: These enzymes cleave nucleotides one at a time from the ends of the polynucleotide chain. They can work from either the 5' end or the 3' end.

3. **Analyzing the Options**:
- The question specifies that we are looking for nucleases that cleave nucleotides from the ends of the polynucleotide chain.
- The options given are:
- A) Specific for 5' end of RNA strand
- B) Specific for 3' end of RNA strand
- C) Specific for both 5' and 3' ends of nucleotide strand
- D) Specific for both 5' and 3' ends of nucleotide strand (this option is repeated, indicating a possible error in the question).

4. **Identifying the Correct Answer**:
- Since exonucleases can act on both the 5' and 3' ends of nucleic acids, the most accurate answer would be that they are specific for both ends.
- Therefore, the correct answer is **C) Specific for both 5' and 3' ends of nucleotide strand**.

### Final Answer:
The nucleases cleaving nucleotides one at a time from the end of the polynucleotide chain are **specific for both 5' and 3' ends of nucleotide strand**.