NEET Zoology Biotechnology Principles and Processes Questions Solved



(a) Identify the selectable markers in the diagram of  E. coli vector shown above.

(b) How is the coding sequence of α-galactosidase considered a better marker than the ones identified by you in the diagram ? Explain.

(a) 'a' is ampR (Ampicillin resistance)

     'b' is tetR (Tetracycline resistance).

(b) 1. Recombinants and non - recombinants are differentiated on the basis of their ability to produce colour in the presence of a chromogenic substrate.

2. In this a recombinant DNA is inserted within the coding sequence of α-galactosidase. It inactivates the enzyme. This is called insertional inactivation.

3. Recombinants do not produce blue colour as rDNA is present in the plasmid which results into insertional inactivation of the α-galactosidase.

4. Non -recombinants produce blue colour in presence of chromogenic substrate as the plasmid in the bacteria does not have rDNA.

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