AP BIOLOGY

Detailed explanation-1: -Bacteria carrying recombinant plasmids therefore form white colonies. To screen bacterial colonies, the chromogenic substrate X-Gal and the gratuitous inducer IPTG are mixed with suitable dilution of a culture, combined with molten top agar, and then spread on agar plates containing the appropriate antibiotic.

Detailed explanation-2: -The most accurate way to verify your recombinant colonies is by Sanger sequencing. Plasmid DNA is first isolated from an overnight bacterial culture. Once completed, the insert can be identified using sequencing primers appropriate for the selected vector.

Detailed explanation-3: -Blue-white screening is a rapid and efficient technique for the identification of recombinant bacteria. It relies on the activity of -galactosidase, an enzyme occurring in E. coli, which cleaves lactose into glucose and galactose.

Detailed explanation-4: -Cells transformed with vectors containing recombinant DNA will produce white colonies; cells transformed with non-recombinant plasmids (i.e. only the vector) grow into blue colonies.

Detailed explanation-5: -Assertion: : Insertion of recombinant DNA within the coding sequence of beta-galactosidase results in colourless colonies. Reason: Presence of insert results in inactivation of enzyme beta-galactosidase known as insertional inactivation.