Telomerase is an enzyme that adds DNA sequence repeats (“TTAGGG” in all vertebrates) to the 3′ end of DNA strands in the telomere regions, which are found at the ends of eukaryotic chromosomes. The telomeres contain condensed DNA material, giving stability to the chromosomes.
Telomerase was discovered by Carol W. Greider and Elizabeth Blackburn in 1985 in the ciliate Tetrahymena. Together with Jack W. Szostak, Greider and Blackburn were awarded the 2009 Nobel Prize in Physiology or Medicine for their discovery.
Picture of telomeres below.
Information taken in part from Wikipedia.