How Telomeres Work

Telomeres (in white) cap the ends of human chromosomes, protecting the genetic information from damage.
Telomeres (in white) cap the ends of human chromosomes, protecting the genetic information from damage.
Image courtesy the ­Human Genome Program

­The 1982 science fiction classic "Blade Runner" pulses with dystopian ponderings about the human condition -- plus it's highly quotable. There's hardly a Rutger Hauer line in the film that hasn't been sampled by a DJ or used as a MySpace headline. In one scene, Hauer's character -- an artificial human with a mere four-year life span -- confronts the scientist who created him. He makes a very human demand: "I want more life."

As a race, we spend a great deal of time fleeing from our own mortality. After all, the will to survive is essential to our genetic mission to propagate the species. In our more ambitious moments, we even dare dream of immortality. "The Epic of Gilgamesh," the oldest-known written text, explored this topic more than four millennia ago. Why do we die? What if we could live forever?

­While the philosophic aspects of these questions will likely remain a matter of discussion for ages to come, modern science has made startling headway in the study of telomeres. Discovered in 1938 by gen­eticist Hermann J. Müller, telomeres (Greek for "end part") are essentially protective caps composed of short DNA sequences on the tips of chromosomes. The chromosomes they protect, in turn, contain the DNA that determines our entire biologic profile [source: Huaire]. Geneticist Elizabeth Blackburn compared them to the little plastic caps on the ends of your shoelaces. Without them, the laces begin to unravel.

Each time a cell divides, however, the telomeres become shorter. If they grow too short, they reach the Hayflick limit, the point at which they can no longer protect the chromosomes from damage. In this, they sound less like the ends of shoelaces and more like a lit candle. Even now, your telomeres may grow shorter with each cell division, burning down ever closer to the point of guttering out.

­We fear the­ inevitable­ darkness -- ponder its immeasurable depths. Might telomere research hold the key to not only staving off death, but defeating it?