Question

Select markers help us in identifying and eliminating non transformed cells during gene cloning. Explain how the gene for beta galactosidase enzyme works as a select able marker?

Answer 1

When recombinant DNA inserted within the coding sequence of the enzyme beta galactosidase, the gene for the enzyme production is removed, after this colonies are transferred into growing medium containing chromogenic substrate, non-transformed colonies give blue colour but transformed colonies not give any colour due to insertional inactivation.