Which of the following enzymes affect the process of synthesis of new DNA chain?

Options

A. Restriction endonuclease
B. Mutase
C. Ribonuclease
D. Polymerase ।

Answer

To determine which enzyme affects the process of synthesis of a new DNA chain, we will analyze each of the provided options.

### Step-by-Step Solution:

1. **Understanding the Question**: We need to identify which enzyme is involved in the synthesis of a new DNA chain.

2. **Evaluating the Options**:
- **Option 1: Restriction Endonucleases**:
- These enzymes are known for cutting DNA at specific sites. They are primarily used in molecular cloning and do not play a role in synthesizing new DNA chains.
- **Conclusion**: This option does not affect the synthesis of new DNA.

- **Option 2: Mutase**:
- Mutases are enzymes that belong to the isomerase class. They facilitate the rearrangement of functional groups within a molecule but do not directly participate in DNA synthesis.
- **Conclusion**: This option does not affect the synthesis of new DNA.

- **Option 3: Ribonuclease**:
- Ribonucleases are enzymes that degrade RNA into smaller components. Their function is related to RNA metabolism and does not involve DNA synthesis.
- **Conclusion**: This option does not affect the synthesis of new DNA.

- **Option 4: Polymerase I**:
- DNA Polymerase I is an enzyme that plays a crucial role in DNA replication. It synthesizes new DNA strands by adding nucleotides to a growing DNA chain, thus directly affecting the synthesis of new DNA.
- **Conclusion**: This option is correct as it affects the synthesis of new DNA.

3. **Final Answer**: The enzyme that affects the process of synthesis of a new DNA chain is **Polymerase I**.