Enzymes that cleave nucleic acids within the polynucleotide chain is known as

Options

A. endonuclease
B. exonuclease
C. arlsulfatase
D. phosphotriesterase

Answer

To solve the question "Enzymes that cleave nucleic acids within the polynucleotide chain is known as," we will analyze the options provided and identify the correct answer step by step.

### Step-by-Step Solution:

1. **Understanding the Term Nuclease**:
- Nucleases are enzymes that cut nucleic acids (DNA or RNA). They can be classified based on where they cut the nucleic acid chain.

2. **Analyzing the Options**:
- **Option 1: Endonuclease**:
- The prefix "endo-" means "inside." Endonucleases cleave the nucleic acid chain at specific sites within the polynucleotide chain, not at the ends.
- **Option 2: Exonuclease**:
- The prefix "exo-" means "outside." Exonucleases remove nucleotides one at a time from the ends of the polynucleotide chain (either 5' or 3' end).
- **Option 3: Arylsulfatase**:
- This enzyme cleaves sulfate groups from aryl sulfates and is not related to nucleic acids.
- **Option 4: Phosphotriesterase**:
- This enzyme cleaves phosphotriester bonds, which are rare and not directly involved in cleaving nucleic acids.

3. **Identifying the Correct Answer**:
- Since the question specifically asks for enzymes that cleave nucleic acids **within** the polynucleotide chain, the correct answer is **Endonuclease**. This enzyme cuts the nucleic acid at internal sites rather than at the ends.

### Final Answer:
The enzymes that cleave nucleic acids within the polynucleotide chain are known as **Endonucleases**.

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