Class 12th Biology 2017 Set2 Delhi Board Paper Solution
Explain the role(s) of the following in biotechnology.
(c) Selectable markers in pBR322
Selectable Markers in pBR322 pBR322, an E. coli cloning vector has two antibiotic resistance genes, i.e. for ampicillin and tetracycline. Antibiotic resistance is used as selectable marker, i.e. it helps in identification and selection of transformants. For example, when a foreign DNA is ligated at the site of tetracycline resistance (tet r ,) gene in pBR322, the recombinant plasmid will lose tetracycline resistance due to insertional inactivation of foreign DNA, but can still be selected out from non-recombinants by placing the transformants on ampicillin containing medium. The transformants growing on ampicillin containing medium, are then transferred on tetracycline containing medium. The recombinants will grow on ampicillin containing medium but not on tetracycline one whereas non-recombinants grow on both.
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