We've long thought that our genetic material, our DNA, is filled with junk. No, not old tires and discarded refrigerators, but DNA that didn't seem to do anything. We've thought that the main job of DNA was to produce the proteins that speed up chemical reactions in the body and make up much of the body's structure. Protein-producing DNA works by being copied to RNA that instructs the protein-producing machinery. The difficulty is that only about 1.5% of our total DNA actually codes for proteins; yet, at the same time, most of the DNA is copied into RNA, a wasteful process if most of the RNA isn't used.
Now, there's increasing evidence that the so-called junk DNA
actually has a vital role. It looks very much like the copied RNA actually does much of
the regulation of the genetic material, telling genes when to turn on and when to turn
off, and even guiding the same gene to produce different products. Indeed, our complex
bodies may be possible only because of what we've thought was junk!
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.