A Vector DNA is a small piece of DNA containing regulatory and coding sequences of interest. A vector is a DNA molecule into which foreign fragments of DNA may be inserted. A vector functions like a "molecular carrier", which will carry fragments of DNA into a host cell. Vectors are usually derived from plasmids, which are small, circular, double-stranded DNA molecules occurring naturally in the cytoplasm of bacteria. Vectors contain an origin of replication, which enables the vector, together with the foreign DNA fragment inserted into it, to replicate. Vectors contain genetic markers that allow for selection of cells which have taken up the plasmid DNA. Vector DNA functions to insert and amplify a gene into a target genome. Vector DNA can be used in a DNA vaccine.
