We inherit our genetic material from our mothers and fathers, receiving, with a couple of exceptions, equal amounts from each parent. The exceptions include the relatively few genes on the Y chromosome, exclusive to males. The other exception is more interesting. Mitochondria are small subunits of cells involved in fulfilling energy requirements. They almost certainly originated as separate organisms, single celled bacteria that took up life inside of other cells and eventually were incorporated into those cells. Today, we can't live without them.
But back to inheritance. Not surprisingly, having descended from
bacteria, mitochondria have their own genetic material, DNA. Furthermore, all of the
mitochondria of an individual are passed on from the mother, from mitochondria
originally within the egg and reproduced by simple fission, similar to the reproduction
of bacteria. Since mitochondrial DNA mutates, we can follow genetic lineages
nicely—with the stipulation that it follows only the female line. You may recall the
so-called African Eve a few years back. Simply a consequence of following lineages of
mitochondrial DNA back to a single ancestor—female ancestor, that is.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.