Question

Select the incorrect statement.

• A. Selection of recombinants due to inactivation of antibiotic is a cumbersome procedure.
• B. Insertional inactivation of $\beta $ -galactosidase leads to colourless colonies.
• C. Insertional inactivation of $\beta $ -galactosidase leads to blue color colonies.
• D. In insertional inactivation, the rDNA is inserted within the coding sequence of an enzyme $\beta $ -galactosidase.

Answer 1

Answer: (C)

In PUC plasmid having Lac Z gene as selectable marker, it produces enzyme $\beta $ -galactosidase. If bacteria having PUC plasmid is grown in medium having chromogenic substrate, than non recombinants produces colourless colonies and in recombinants due to insertional inactivation $\beta $ -galactosidase is not produced thus colourless colonies are produced.