Telomerase
Telomerase (transferase) is a ribonucleoprotein that adds a species-dependent telomere repeat sequence to the 3' end of telomeres. A telomere is a region of repetitive sequences at each end of a eukaryotic chromosomes in most eukaryotes. Telomeres protect the end of the chromosome from DNA damage or from fusion with neighbouring chromosomes. It plays roles in senescence, oncogenesis, chromosomal repair, aging and antiapoptosis etc.