BIOTECHNOLOGY- COMPETENT HOST

 RECOMBINANT DNA can be introduced into the bacterial cell by TRANSFORMATION. 

TRANSFORMATION is the uptake of naked DNA by bacterial cells. In order to force bacteria to take plasmid or recombinant DNA, the bacterial cells are made competent. This is done by treating bacteria with divalent cations such as calcium which increases the efficiency with which DNA enters the bacterium through the pores in its cell wall.

Recombinant DNA is incubated with bacterial cells on ice, followed by placing them briefly at 42⁰ C and again placing them on ice. This creates a heat shock and makes bacterial cells competent.

In ANIMAL cells DNA can be introduced using a method called MICROINJECTION. In this recombinant DNA is directly injected into the cell.

In PLANTS, BIOLISTICS OR GENE GUN technique is used to transfer recombinant DNA. In this technique plant cells are bombarded with micro particles of gold and tungsten coated with recombinant DNA.