Aging is a biological process that affects most cells, organisms, and species. Telomeres, located at the end of chromosomes, have been postulated as a universal biological clock that shortens in parallel with aging in cells. Telomeres shorten as cells age. They consist of an evolutionarily conserved repetitive nucleotide sequence ranging in length from a few hundred base pairs in yeast to several kilobase pairs in vertebrates. More information:Telomere Biology