In the process of insertional inactivation

Options

A. a recombinant DNA is inserted within the coding sequence of enzyme `beta`-galactosidase, resulting in inactivation of the enzyme
B. a recombinant DNA is inserted within the coding sequence of proteins involved in the replication of the plasmid
C. a recombinat DNA is inserted within the recongnition site for EcoRl
D. none of the

Answer

A

Explanation

Alternative selectable markers have been developed which differentiate recombinants from the non-recombinants on the basis of their ability to produce colour in the presence of a chromogenic substrate. In this, a recombinantDNA is inserted within the coding sequence of an enzyme, `beta`-galactosidase. This results into inactivation of the enzyme, whcih is referred to as insertional inactivation. The presence of a chromogenic substrate given blue coloured colonies if the plasmid in the bacteria does not have an insert. Presence of insert results into insertional inactivation of the `beta`-galactosidase and the colonies do not produce any colour, these are identified as recombinant colonies.