Question

Why does the ‘insertional inactivation’ method to detect recombinant DNA is preferred to ‘antibiotic resistance’ procedure?

Answer 1

1. Selection of recombinants due to inactivation of antibiotics is a cumbersome procedure because it requires simultaneous plating on two plates having different antibiotics.
2. In the insertional inactivation method, insertion of recombinant DNA within the coding sequence of the enzyme beta-galactosidase results into inactivation of this enzyme, and the colonies do not produce any colour. The presence of a chromogenic substrate gives blue-coloured colonies in the absence of an insert.