A segment of DNA (e.g., an R-factor gene) that has a repeat of an insertion sequence element at each end that can migrate from one plasmid to another within the same bacterium, to a bacterial chromosome, or to a bacteriophage; the mechanism of transposition seems to be independent of the host's usual recombination mechanism.jumping gene, transposable element [L. transpono, pp. transpositum, to transfer, + -on]