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

A. Replica plating. 

• Host cells are first plated (master plate) on solid media with the desired antibiotic overnight. 
• Velvet paper is aligned, pressed on master plate. 
• With the same alignment it is pressed onto the replica plate. 
• Keep it overnight, transformed colonies will not grow in replica plate. 
• The colonies having insert can easily be scored off from master plate by comparing the two plates.