A method of vectorless DNA transfer is:

Options

A. microinjection
B. electroporation
C. biolistics
D. all of these

Answer

**Step-by-Step Solution:**

1. **Understanding Vectorless DNA Transfer**: Vectorless DNA transfer refers to methods that allow the introduction of foreign DNA into a cell without the use of a vector (like plasmids or viruses).

2. **Identifying Methods of Vectorless DNA Transfer**: The question provides several options: microinjection, electroporation, and biolistics. We need to evaluate each method to determine if they qualify as vectorless DNA transfer techniques.

3. **Microinjection**:
- In this method, a fine glass pipette is used to inject foreign DNA directly into the nucleus of a cell.
- The pipette's diameter is much smaller than the cell, allowing precise delivery of DNA.
- This method does not require a vector, making it a vectorless DNA transfer technique.

4. **Electroporation**:
- This technique involves applying a high-voltage pulse to cells, which temporarily disrupts the cell membrane.
- The disruption allows foreign DNA or nucleic acids to enter the cell.
- Since no vector is used in this process, it is also classified as a vectorless DNA transfer method.

5. **Biolistics (Gene Gun Method)**:
- In biolistics, microscopic gold or tungsten particles coated with foreign DNA are fired into cells using a compressed air gun.
- This method directly delivers DNA into the cells without the need for a vector.
- Therefore, it is also a vectorless DNA transfer technique.

6. **Conclusion**: Since all three methods—microinjection, electroporation, and biolistics—are methods of vectorless DNA transfer, the correct answer to the question is "all of these."

**Final Answer**: All of these (microinjection, electroporation, biolistics) are methods of vectorless DNA transfer.

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