What is the purpose of a divalent cation treatment in making bacterial cells competent for DNA uptake?

To alter the permeability of the cell membrane

(d) To alter the permeability of the cell membrane

The purpose of treating bacterial cells with a divalent cation, such as calcium, is to alter the permeability of the cell membrane and make the cells competent for DNA uptake.

Competent cells are able to take up foreign DNA more efficiently through pores or channels in the cell membrane. The divalent cation treatment enhances the ability of DNA to enter the bacterial cells, allowing for the successful introduction of recombinant DNA into the cells during transformation.