Which is not a method for the introduction of recombinant DNA into host cells?

Options

A. Electroporation
B. Biolistics
C. Transfection
D. Restriction digestion

Answer

To determine which method is not used for the introduction of recombinant DNA into host cells, we will analyze the four options provided.

### Step-by-Step Solution:

1. **Understand the Options**: We have four methods listed:
- A) Electroportation
- B) Biolistic
- C) Transfection
- D) Restriction Digestion

2. **Analyze Each Method**:
- **Electroportation**: This method involves applying an electric field to cells to increase the permeability of the cell membrane, allowing DNA to enter. This is indeed a method for introducing recombinant DNA into host cells.

- **Biolistic**: Also known as the gene gun method, this technique uses high-speed particle bombardment to introduce DNA into cells. This is also a valid method for introducing recombinant DNA.

- **Transfection**: This process involves the deliberate introduction of nucleic acids into eukaryotic cells. This is a recognized method for introducing recombinant DNA into host cells.

- **Restriction Digestion**: This process involves cutting DNA into smaller fragments using restriction enzymes. While it is a crucial step in DNA manipulation, it does not involve the introduction of DNA into host cells.

3. **Identify the Incorrect Method**: Based on the analysis, the method that does not introduce recombinant DNA into host cells is **D) Restriction Digestion**.

### Final Answer:
The method that is not used for the introduction of recombinant DNA into host cells is **D) Restriction Digestion**.