The Dynamic Genome:

Mobile Genetic Elements
In the 1950s Barbara McClintock observed an
unusual phenomenon during her genetic investigations
of Indian corn (maize, Zea mays),
namely, “jumping genes” (mobile genetic elements).
A mobile element causes a break in a
chromosome at the site of an insertion and
causes a gene locus to move to a different location
in the chromosome (transposition). During
the last 25 years, mobile elements have been
found in every organism in which they have
been sought: in bacteria, in Drosophila, in the
nematode C. elegans, and in mammals, including
man. These observations have resulted in
the concept of a dynamic genome that is by no
means fixed and unchangeable. Mutations due
to mobile elements inserted into genes have
also been demonstrated in man.