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The 2009 Nobel Prize in physiology¹ or medicine goes to Harvard’s Jack² Szostak, Johns Hopkins’s Carol Greider and Elizabeth Blackburn at U.C. San Francisco for their work on how chromosomes³ are protected by telomeres and the enzyme⁴ telomerase.

The Nobel laureates’ research helped explain how an organism’s DNA⁵ is successfully copied when cells divide. Telomeres are genetic⁶ sequences that act like little protective caps at the end of chromosomes—think of the sealed tips of your shoelaces. Telomerase is the enzyme that builds telomeres.

Blackburn and Szostak determined⁷ that it was a specific DNA sequence in the telomeres that kept chromosomes from fraying⁸ whenever they were copied when a cell splits in two. Blackburn and Greider discovered telomerase. The findings have implications for the understanding of aging and cancer. Because if the enzyme keeps the telomeres robust⁹, the chromosomes stay protected and the cell’s aging is slowed. And in cancer cells, which unfortunately do not seem to age, telomere length is maintained virtually indefinitely. Szostak, Greider and Blackburn thus revealed one of life’s basic mechanisms¹⁰, and paved the way for new medical strategies.