Final answer:
Telomerase is a ribonucleoprotein complex that extends telomeres using an RNA template, vital for the replication and maintenance of chromosomes, primarily in germ and stem cells and is active in many cancer cells.
Step-by-step explanation:
Telomerase is a ribonucleoprotein complex assembled in the nucleus and binds to the telomeric region. This complex enzyme is essential for the maintenance of chromosome integrity, particularly at the ends where telomeres are located.
Telomerase consists of a protein component with reverse transcriptase activity, known as Telomerase Reverse Transcriptase (TERT), and an RNA component that serves as a template for DNA synthesis, called the Telomerase RNA Component (TERC). As a catalytic ribonucleoprotein, telomerase adds DNA sequence repeats to the 3' end of the telomeres, utilizing an inbuilt RNA template to extend the telomeric DNA.
Telomerase activity is crucial in germ cells, adult stem cells, and many cancer cells, as it provides a mechanism for cells to avoid the shortening of chromosomes that would otherwise occur during replication. The discovery of telomerase and its functions by Elizabeth Blackburn, Carol W. Greider, and Jack Szostak was recognized with the Nobel Prize for Medicine or Physiology in 2009.