vector (genetic)

Last reviewed 01/2018

Genetic vectors are molecules which are capable of independent replication when placed into a bacterial cell host. They are essential to genetic engineering as a means of conveying desired genetic sequences to an environment where they can be produced in large quantities.

Genetic vectors include:

  • plasmids: circular, small DNA rings separate from the main chromosomes and widely found in bacteria
  • bacteriophages: bacterial viruses capable of multiplying within bacteria
  • cosmids: a combination of plasmids packaged into bacteriophages

Vectors are selected in which a given site on their DNA is complementary for a sequence at the ends of the gene of interest. The site is largely determined by the base pairs cleaved by a restriction enzyme. The enzyme cleaves the vector DNA at the site and the foreign DNA is inserted by a DNA ligase enzyme.