DNA is a hydrophilic molecule, so it cannot pass through cell membranes. Then how does a recombinant DNA inserted into a plasmid vector, enter into a bacterial cell ?

Explanation

This is done by treating them with a specific concentration of a divalent cation such as calium, which increases the efficiency with efficiency with which DNA enters the bacterium through pores in its cell wall. Recombinant DNA can be then forced into such cells by incubating the cells with recombinant DNA on ice, followed by placing them briefly at `42^(@) C` and then putting them back on ice. This enables the bacteria to take up the recombinant DNA .