Telomerase-

By using TERC, TE can add a six-nucleotide repeating sequence, 5'-TTAGGG (in veebrates, the sequence differs in other organisms) to the 3' strand of chromosomes. These TTAGGG repeats (with their various protein binding paners) are called telomeres. The template region of TERC is 3'-CAAUCCCAAUC-5'. Telomerase can bind the first few nucleotides of the template to the last telomere sequence on the chromosome, add a new telomere repeat (5'-GGTTAG-3') sequence, let go, realign the new 3'-end of telomere to the template, and repeat the process. Telomerase reverses telomere shoening.