Define insertional inactivation.

Insertional inactivation is a technique used in recombinant DNA technology. In this procedure, a bacteria carrying recombinant plasmids or a fragment of foreign DNA is made to insert into a restriction site inside a gene to resist antibiotics, hence causing the gene to turn non-functional or in an inactivated state.

An example of this is a pUC19 plasmid vector in which the lacZ gene that encodes for beta-galactosidase can no longer be produced upon the insertion of a foreign gene. Selection or screening is a fundamental process in which once the recombinant DNA is inserted into a particular host cell, it becomes necessary to detect the cells that have received the recombinant or foreign DNA molecules.

This process is referred to as screening or selection. It is based on non-expression or expression of certain traits or characteristics. Insertional inactivation is an effective method of screening. In this procedure, one of the genetic characteristics is disturbed by the introduction of foreign DNA. One of the most influential selection methods of recombinant plasmid for the insertional inactivation procedure is a method known as ‘Blue-white’ selection method.