Significance of 'heat shock' method in bacterial transformation is to facilitate

Options

A. Uptake of DNA through transient pores in the bacterial cell wall
B. Binding of DNA to the cell wall
C. Release of DNA through membrane transport proteins
D. Expression of antibiotic resistance gene

Answer

### Step-by-Step Text Solution:

1. **Understanding the Heat Shock Method**: The heat shock method is a technique used in molecular biology to facilitate the transformation of bacteria. It involves subjecting bacterial cells to a sudden increase in temperature, typically after they have been incubated with plasmid DNA.

2. **Role of Bivalent Cations**: In this method, bivalent cations, such as calcium ions (Ca²⁺), are often used. These ions help to stabilize the bacterial cell membrane and make it more permeable.

3. **Formation of Transient Pores**: The heat shock treatment causes the bacterial cell membrane to undergo a physical change, resulting in the formation of transient pores. These pores allow the foreign DNA (plasmid) to enter the bacterial cell.

4. **Uptake of DNA**: The primary significance of the heat shock method in bacterial transformation is to facilitate the uptake of DNA through these transient pores in the bacterial cell wall. This allows for the introduction of new genetic material into the bacteria.

5. **Elimination of Other Options**:
- **Binding of DNA to the cell wall**: This is not the main function of the heat shock method; it is about uptake, not binding.
- **Release of DNA through membrane transport proteins**: The heat shock method does not involve transport proteins; it relies on the transient pores created by the heat shock.
- **Expression of antibiotic resistance gene**: While transformed bacteria can express antibiotic resistance genes, the heat shock method itself is not directly responsible for this expression.

6. **Conclusion**: Therefore, the correct answer to the question is that the significance of the heat shock method in bacterial transformation is to facilitate the uptake of DNA through transient pores in the bacterial cell wall.