NCERT · Class 12 · Biology · Biotechnology: Principles and ProcessesExplain Insertional Inactivation.

Insertional inactivation is a sophisticated screening method used to identify recombinant bacteria based on the disruption of a marker gene. When a foreign DNA fragment is inserted directly into the coding sequence of an enzyme gene, such as the lacZ gene encoding beta-galactosidase, the gene becomes non-functional. Consequently, recombinant colonies fail to produce the active enzyme and cannot convert a colorless substrate into a blue-colored product, allowing easy visual distinction from non-recombinant blue colonies.