Describe the role of CaCl, in the prepration of competent cell.

Explanation

Since, DNA is a hydrophilic molecule, it cannot pass through the cell membrane. In order to force the bacteria to take up the plasmid, the bacterial cells must first be made competent to take up foreign DNA. This is done by treating them with a specific concentration of a divalent cation such as calcium `(Ca^(2+))`, which increases the efficiency with which DNA enters the bacterium through the pores on its cell wall.
Recombinant DNA can then be forced into such cells by incubating the cells with recombinant DNA ice, cold solution of calcium chloride followed by subjecting them briefly into heat shock at `42^(@)C` and then putting them back on `CaCl_(2)` solution. This enables the bacteria to take up the recombinant DNA.