Over time our chromosomes – the tight bundles of DNA that contain all our genetic information, pictured in blue – start to deteriorate at the tips like a loose piece of string fraying at the ends. So like shoelaces have that little protective aglet, chromosomes have telomeres (highlighted here in white) at their extremes – repetitive sections of DNA that act as a buffer against the wear and tear of life, taking the hit each time a cell divides. They can do this, as Carol Greider – born on this day – co-discovered in 1984, because a molecule called telomerase rebuilds their scraggly ends each time. But eventually even telomerase tires of its duty and as its efficiency declines, so does a cell’s health, making telomerase pivotal to many diseases, and so crucial to medicine that it earned Greider a share of a Nobel Prize in 2009.
Written by Anthony Lewis
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