Describe the role of $CaCl_2$ in the preparation of competent cells.

(N/A) The preparation of competent cells is a crucial step in the process of transformation,where a host cell takes up foreign $DNA$.
$CaCl_2$ (calcium chloride) is used to treat bacterial cells to make them competent.
The divalent $Ca^{2+}$ ions increase the efficiency with which $DNA$ enters the bacterium through pores in its cell wall.
This is achieved by creating a charge neutralization effect between the negatively charged $DNA$ molecules and the negatively charged bacterial cell membrane,facilitating the uptake of recombinant $DNA$ during the heat shock process.