Question

Selection is an important step in genetic engineering. You are given ampicillin and tetracycline antibiotics. Using these antibiotics, which selection technique could be used to differentiate between recombinant and non-recombinant cells?

Answer 1

Replica plating.

Plasmid pBR322 carrying the insert in tet^r gene in Multiple Cloning Sites (MCS) is used to transform the host cells which are first plated on solid media containing ampicillin. Overnight colonies from every single cell plated will develop which all have the plasmid. Replica plating is next performed to select colonies from this plate which are tetracycline sensitive due to insertional inactivation. The non recombinant colonies will grow on media with tetracycline and thus differentiate between recombinant and non recombinant cells.