Which enzyme is useful in genetic engineering ?

Options

A. DNA - ase
B. Amylase
C. Lipase
D. Restriction endonuclease

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks which enzyme is useful in genetic engineering. We need to identify the enzymes listed and their relevance to genetic engineering.

2. **Identifying the Options**: The options provided are DNAs, amylase, lipase, and restriction endonuclease. We will analyze each option to determine its role.

3. **Analyzing Each Enzyme**:
- **DNAs**: This term is vague and does not refer to a specific enzyme. DNA itself is a molecule, not an enzyme.
- **Amylase**: This enzyme is involved in the digestion of carbohydrates by breaking down starch into sugars. It is not used in genetic engineering.
- **Lipase**: This enzyme helps in the digestion of fats by breaking down lipids into fatty acids and glycerol. Like amylase, it does not play a role in genetic engineering.
- **Restriction Endonuclease**: This enzyme is crucial in genetic engineering as it cuts DNA at specific sequences known as restriction sites. This ability to cleave DNA allows scientists to manipulate genetic material, making it essential for cloning, gene splicing, and other genetic engineering techniques.

4. **Conclusion**: Based on the analysis, the enzyme that is useful in genetic engineering is **restriction endonuclease**.

### Final Answer:
The enzyme useful in genetic engineering is **restriction endonuclease**.

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