Insertion of Foreign Gene into a Cloning Vector

The foreign (passenger) DNA is next inserted into a cloning vector, or vehicle DNA. The most commonly used cloning vectors are bacterial plasmids and bacteriophage viruses such as lambda phage and M13, with pBR322 being the plasmid most commonly used of all.

The vector plasmid is isolated from its host bacterium and then cut using the same restriction enzyme that was used to isolate the desired gene from the donor DNA, so that the cut ends of both pieces of DNA are compatible with each other. The enzyme DNA ligase is then used to insert and join the foreign DNA into the cut vector DNA. The combined molecule -- vector DNA plus foreign DNA -- is now called **recombin …