Our DNA exists in discrete lengths called chromosomes. And like books on highly organised library shelves, genes are distributed along them in specific positions. Those at the tips of each chromosome would be vulnerable to damage if not for the telomere – a repetitive DNA sequence that acts like a protective bookend. Telomeres shorten each time a cell divides, but as Elizabeth Blackburn (pictured) – born on this day in 1948 – co-discovered, they are replenished by an enzyme called telomerase. After dividing a number of times, normal cells begin to show signs of age – the rebuilder telomerase tires of its task and telomeres erode. Our cells may ‘age’ and telomeres shorten more rapidly when we are stressed or ill. Consequently, telomere length is now studied as a predictor of health and ageing. For her work revealing the chemistry of life at its extremes, Elizabeth Blackburn was awarded a Nobel Prize in 2009.
Written by Lindsey Goff
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