How do the heat shock and the calcium chloride assist plasmid insertion in this chemical transformation? relate your answer to the charge on dna and to the charge on the plasma membrane of a cell?

The use of calcium chloride for the transformation (incorporation of plasmid DNA into bacteria ) enables the binding of plasmid DNA to lipopolysaccharides (LPS) on the plasma membrane. Positively charged Ca2+ attract both the negatively charged DNA and the negatively charged groups in the LPS.