Question

Explain how is a bacterial cell made ’competent’ to take up recombinant DNA from the medium.

Hint:

In PCR, each cycle doubles the amount of DNA, leading to exponential amplification. The key to success in PCR is using a heat-stable polymerase enzyme like Taq polymerase.

Answer 1

Explain how is a bacterial cell made 'competent' to take up recombinant DNA from the medium.
- Bacterial cells are made competent to take up recombinant DNA through a process called chemical transformation or electroporation.
- In chemical transformation, bacteria are treated with calcium chloride (CaCl$_2$), which makes the cell membrane more permeable. This allows the recombinant DNA to enter the bacterial cell.
- In electroporation, an electrical shock is applied to the bacterial cells, which creates temporary pores in the cell membrane, allowing the DNA to enter.
- After this process, the bacterial cells are incubated, and only the cells that have successfully taken up the recombinant DNA will grow on selective media.