Which of the following methods can be used for making the bacterial cell " competent" ?

Options

A. Treating with specific concentration of divalent cation`(Ca^(2+))`
B. Treating with specific concentration of monovalent cation`(K^(+))`
C. Heat shock
D. Both (1) and (3)

Answer

To determine which methods can be used to make bacterial cells competent, we need to understand the concept of competence in bacteria and the methods used to induce it.

### Step-by-Step Solution:

1. **Understanding Competent Cells**:
- Competent bacterial cells are those that can take up extra chromosomal DNA, such as plasmids. This is crucial for genetic engineering and biotechnology applications.

2. **Methods to Make Bacterial Cells Competent**:
- There are two primary methods for making bacterial cells competent:
- **Calcium Chloride Method**:
- This method involves treating bacterial cells with a specific concentration of divalent cations, such as calcium ions (Ca²⁺). Calcium chloride is commonly used for this purpose.
- The calcium ions help stabilize the cell membrane and facilitate the binding of DNA to the bacterial surface.
- **Heat Shock**:
- After treating the cells with calcium chloride, a heat shock is applied. This involves exposing the cells to a brief period of elevated temperature, which creates pores in the cell membrane and allows DNA to enter the cells.

3. **Evaluating the Options**:
- The question provides several options:
- Option 1: Treating with specific concentration of divalent cation (calcium).
- Option 2: Treating with specific concentration of monovalent cation (potassium).
- Option 3: Heat shock.
- Option 4: Both one and three.
- From our understanding, options 1 and 3 are valid methods for making bacterial cells competent.

4. **Conclusion**:
- The correct answer is option 4, which states that both treating with specific concentration of divalent cation (calcium) and heat shock can be used to make bacterial cells competent.

### Final Answer:
The methods that can be used for making the bacterial cell competent are:
**Option 4: Both 1 and 3 (treating with specific concentration of divalent cation and heat shock).**

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