Question

Explain how to find whether E. coli bacterium has transformed or not, when, a recombinant DNA bearing ampicillin-resistant gene is transferred into it.

Answer 1

The recombinant/transformant may be found out from non-recombinant/non-transformant by plating the transformants on ampicillin containing medium. The transformants growing on ampicillin containing medium are then transferred to tetracycline containing medium. The recombinant will grow on ampicillin containing medium but not on that containing tetracycline. But non-recombinant will grow on both tetracycline and ampicillin containing media.