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. E. coli bearing transferred recombinant DNA are first grown on ampicillin containing medium and then transferred on to a medium containing tetracycline. The transformants will grow only in ampicillin containing medium and not in tetracycline containing medium. The non-transformants, on the other hand, will grow in both the mediums.

b. Ampicillin resistant gene acts as a selectable marker and helps in selecting the transformants.