Manipulation of DNA in genetic engineering became possible due to the discovery of

Options

A. Restriction endonuclease
B. DNA ligase
C. Transcriptase
D. Primase

Answer

To answer the question "Manipulation of DNA in genetic engineering became possible due to the discovery of," we can break down the solution into the following steps:

### Step-by-Step Solution:

1. **Understanding Genetic Engineering**:
- Genetic engineering involves altering the genetic material of an organism. This requires precise manipulation of DNA.

2. **Key Discoveries in DNA Manipulation**:
- The manipulation of DNA was made possible by several key discoveries, particularly the discovery of molecular scissors known as restriction enzymes (or restriction endonucleases).

3. **Role of Restriction Enzymes**:
- Restriction enzymes act like molecular scissors that can cut DNA at specific sites. This is crucial for genetic engineering as it allows scientists to remove or insert specific genes.

4. **Types of Restriction Enzymes**:
- There are two main types of restriction enzymes:
- **Endonucleases**: These cut the DNA at specific internal sites.
- **Exonucleases**: These cut the DNA from the ends.
- Endonucleases are primarily used in recombinant DNA technology.

5. **Example of a Restriction Enzyme**:
- An example of a restriction enzyme is EcoRI, which recognizes a specific palindromic sequence (GAATTC) and cuts the DNA at that site.

6. **Importance of Plasmids**:
- In addition to restriction enzymes, the discovery of plasmids (circular DNA molecules found in bacteria) also played a significant role in genetic engineering. Plasmids can carry foreign DNA and replicate independently within a host cell.

7. **Conclusion**:
- The manipulation of DNA in genetic engineering became possible primarily due to the discovery of restriction enzymes (molecular scissors) and plasmids.

### Final Answer:
The manipulation of DNA in genetic engineering became possible due to the discovery of **restriction enzymes (molecular scissors)**.

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