What is the X in X-mas?
transposon trans·po·son (trāns-pō'zŏn)
A segment of DNA having a repeat of an insertion sequence element at each end as well as genes specific to some other activity such as resistance to antibiotics; it is capable of migrating to a new position within the same or another chromosome, plasmid, or cell and thereby transferring genetic properties.
A segment of DNA that is capable of independently replicating itself and inserting the copy into a new position within the same or another chromosome or plasmid. Transposons act somewhat similarly to viruses and in humans are an underlying cause of hemophilia, certain cancers, and other diseases. In other organisms, they can become a permanent and even beneficial part of the genome, as in maize corn, where transposons account for half the genome, and certain bacteria, where genes for antibiotic resistance can spread by means of transposons. Also called jumping gene.