Cloning vector is a self-replicating DNA molecule that carries foreign DNA insert into a host cell, replicates inside a bacterial (or yeast) cell and amplify to produce many copies of itself and the foreign DNA.
Plasmid: It is an extra chromosomal circular DNA molecule that self replicates inside the bacterial cell and some yeast; cloning limit: 100 to 10,000 base pairs or 0.1-10 kilobases (kb).
Phage : Designed bacteriophage lambda (A.) and Ml 3 : linear DNA molecules, whose region can be replaced with foreign DNA without disrupting its life cycle; cloning limit: 8-20 kb. M13 is a filamentous phage which infects E-coli. Cloning limit: 10 kb.
Cosmids: A constructed extrachromosomal circular DNA molecule that combines features of plasmids and ‘cos’ site of phage ; cloning limit – 45 kb.
Yeast Artificial Chromosomes (YAC) : An artificial chromosome that contains telomeres, origin of replication, a yeast centromere, restriction enzyme site and a selectable marker for identification in yeast cells ; cloning limit: 1 Mb.
