blue–white colour selection

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A common method for identifying bacterial clones that have been successfully transfected with a plasmid vector carrying the sequence of interest. The plasmid has a LacZ gene encoding beta-galactosidase disabled by insertion of the sequence; empty (religated) vectors produce blue colonies when grown on plates containing IPTG and Xgal, but colonies with the insert do not produce functional (beta-galactosidase, and are white.

Subjects: Medicine and Health.

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