Question

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

Answer 1

1. Bacterial cells are frequently treated with a solution containing divalent cations, such as calcium or magnesium, to render them “competent” to absorb recombinant DNA. 
2. This process makes the cell membrane more permeable, which makes it easier for DNA to enter.
3. After being incubated on ice with the recombinant DNA, the cells are briefly heated to 42°C before being put back on ice.
4. The cell membrane develops holes as a result of this quick temperature change, which lets the recombinant DNA in.