Which of the following is not a method of introducing alien DNA into host cells ?

Options

A. Micro injection
B. Heat shock method
C. Being placed along with the cell into a gene gun
D. Gel electrophoresis

Answer

To solve the question "Which of the following is not a method of introducing alien DNA into host cells?", we will analyze each option provided.

### Step-by-Step Solution:

1. **Identify the Methods of DNA Introduction**:
- We need to evaluate each option to determine if it is a method used for introducing foreign DNA into host cells.

2. **Option 1: Microinjection**:
- Microinjection is a method where DNA is directly injected into the nucleus of a cell using a fine glass needle. This is a vectorless gene transfer method commonly used in animal cells.
- **Conclusion**: This is a method of introducing alien DNA into host cells.

3. **Option 2: Heat Shock Method**:
- The heat shock method involves subjecting bacterial cells to a sudden increase in temperature, which makes the cell membrane more permeable. This allows alien DNA to enter the cells, often facilitated by calcium ions.
- **Conclusion**: This is also a method of introducing alien DNA into host cells.

4. **Option 3: Gene Gun (Biolistic Method)**:
- The gene gun method involves coating DNA onto small particles (like gold or tungsten) and shooting them into plant cells. This is another vectorless gene transfer method.
- **Conclusion**: This is a method of introducing alien DNA into host cells.

5. **Option 4: Gel Electrophoresis**:
- Gel electrophoresis is a technique used to separate DNA, RNA, or proteins based on their size and charge. It does not introduce DNA into host cells; rather, it is used for analyzing and separating biomolecules.
- **Conclusion**: This is NOT a method of introducing alien DNA into host cells.

### Final Answer:
The option that is not a method of introducing alien DNA into host cells is **gel electrophoresis**.

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