EXPERIMENTAL FIGURE 6-14 DNA cloning in a plasmid vector permits amplification of a DNA fragment. A fragment of DNA to be cloned is first inserted into a plasmid vector containing an ampicillin-resistance gene (amp^r), such as that shown in Figure 6-13. Only the few cells transformed by incorporation of a plasmid will survive on ampicillin-containing medium. In transformed cells, the plasmid DNA replicates and segregates into daughter cells, resulting in the formation of an ampicillin-resistant colony in which each cell contains the cloned DNA.