Question

(a) Explain how to find whether an E. coli bacterium has transformed or not when a recombinant DNA bearing ampicillin resistant gene is transferred into it.
(b) What does the ampicillin resistant gene act as in the above case?

Answer 1

(a) If E. coli has been transformed, then these ‘transformed E. coli’ cells would be able to grow on ampicillin medium. If the gene of interest (recombinant DNA) is inserted between the ampicillin gene, as a result, the ampicillin is not functional and hence, that E. coli will not be ampicillin resistant and will not grow on ampicillin resistant medium.

(b) Ampicillin resistant gene acts as a selectable marker in this case.