Telomerase is an enzyme that adds telomere repeat sequences to the 3' end of DNA strands. By lengthening this strand DNA polymerase is able to complete the synthesis of the "incomplete ends" of the opposite strand.
* is a ribonucleoprotein;
* Its single RNA molecule provides an AAUCCC (in mammals) template to guide the insertion of TTAGGG.
* Its protein component — called TERT ("TElomere Reverse Transcriptase") — provides the catalytic action.
* Thus telomerase is a reverse transcriptase; synthesizing DNA from an RNA template.