AP BIOLOGY

Detailed explanation-1: -Hence, due to the insertional inactivation of alphagalactosidase in recombinant bacteria, the colonies of recombinant bacteria appear white in comparison to the blue colonies of non-recombinant bacteria.

Detailed explanation-2: -Blue colonies therefore show that they may contain a vector with an uninterrupted lacZ (therefore no insert), while white colonies, where X-gal is not hydrolyzed, indicate the presence of an insert in lacZ which disrupts the formation of an active -galactosidase.

Detailed explanation-3: -The blue colonies contain bacteria with functional -galactosidase, indicating the plasmid taken up during transformation did not contain the DNA of interest.

Detailed explanation-4: -One of the most influential selection methods of recombinant plasmid for the insertional inactivation procedure is a method known as ‘Blue-white’ selection method. In this procedure, the lacZ gene which is a reporter gene is inserted in the vector.

Detailed explanation-5: -(b) Insertional inactivation is the loss of the function of a gene such as alpha-galactosidase gene in plasmid due to insertion of foreign DNA / transgene within it. This tool is used to select recombinants.