In most normal human somatic cells, telomeres shorten with each division. In stem cells and in cancer cells, however, telomeric length is maintained. In the synthesis of telomeres: O the RNA of telomerase serves as a primer. O the direction of synthesis is 3'~5'. O the shorter, 3'~5' strand gets extended. O Telomerase, a ribonucleoprotein, provides both the RNA and the polymerase needed for synthesis. O the polymerase of telomerase is a DNA-directed DNA polymerase.