Question

Why is it difficult for DNA to pass through cell membrane? How the bacterial cells can be made competent to take up DNA?

Answer 1

Since the DNA is a hydrophilic molecule, it cannot pass through cell membranes, In order to force bacteria to take up the plasmid, the bacterial cells must first be made competent to take up DNA. This is done by treating them with a specific concentration of a divalent cation such as calcium