Cloning vectors are DNA molecules used to carry foreign DNA into a host cell. Common vectors include plasmids, bacteriophages, and cosmids. The choice of vector depends on the size of the DNA fragment and the type of host cell used. Host cells are the cells into which the recombinant DNA is introduced for replication. Common host cells include Escherichia coli (E. coli) for bacterial cloning and yeast or mammalian cells for eukaryotic cloning. The host cell provides the necessary machinery for DNA replication and, in some cases, protein expression.
