Plasmid cloning vectors contain different components that help in successful cloning of gene of interest. These components are:
Cloning sites: Cloning sites refer to the recognition sites for restriction enzymes (such as EcoRI, Hind III, PvuI , BamHI, etc.) present on cloning vector. These are the sites where restriction enzymes cut the DNA of vector and insert foreign DNA into it.
Origin of replication (Ori): Origin of replication starts here because this site attracts some proteins which help in the opening and unwinding of DNA and this leads to the initiation of replication.
Selectable markers: These are the DNA segments present on vector that help to select transformants from the populations of organisms. Transformants are those host organisms which successfully take up the recombinant molecule of DNA after the process of transformation. Recombinant molecule of DNA is formed by using a suitable cloning vector and gene of interest. The selectable markers present on vector are antibiotic resistance gene and β galactosidase.