How is the bacterial cell made competent to receive recombinant DNA? Explain. (2 marks)
(i) In order to force bacteria to take up the plasmid, the bacterial cells must first be made 'competent'
to take up DNA.
(ii) This is done by treating them with a specific concentration of a divalent cation, such as calcium,
which increases the efficiency with which DNA enters the bacterium through pores in its cell wall.
(iii) Recombinant DNA can then be forced into such cells by incubating the cells with recombinant DNA
on ice, followed by placing them briefly at (heat-shock) and then putting them back on ice
which enables the bacteria to take up recombinant DNA.