AP BIOLOGY

Detailed explanation-1: -The colonies formed by non-recombinant cells, therefore appear blue in color while the recombinant ones appear white.

Detailed explanation-2: -Any colony containing the plasmid (and therefore the functioning -galactosidase gene) will turn blue, a result of the -galactosidase activity. This is called -complementation.

Detailed explanation-3: -In case of recombinant cells, -complementation does not occur, thus producing no blue colour. 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-4: -Blue colonies contain a plasmid, however they are producing ß-galactosidase (evident by their ability to convert X-GAL into a blue precipitate) indicating that they do not contain inserts.

Detailed explanation-5: -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.