NEET Zoology Biotechnology Principles and Processes Questions Solved


(a) Name the selectable markers in the cloning vector pBR332 ? Mention the role they play.

(b) Why is the coding sequence of an enzyme β-galactosidase a preferred selectable marker in

      comparison to the ones named above ?            (3 marks)

(a) Selectable markers in pBR322 :

      ampR - Ampicillin resistance gene

      tetR - Tetracycline resistance gene

       Role of selectable markers. They help in identifying and eliminating non-transformants/non-

       recombinants and selecctively permitting the growth of transformants and recombinants.


(b)  (i) Using β-galactosidase as selectable marker is a simpler process and less cumbersome.

 (ii) In the presence of chromogenic substrates recombinants are colourless and non-recombinants

      are blue in colour. Non-recombinants produce blue colour in the presence of chromogenic subs-

      trate as the plasmid in the bacteria does not have rDNA.

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