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Telomerase is an enzyme responsible for the elongation and maintenance of telomeres, the protective regions at the ends of chromosomes. Telomerase is composed of two key components: a reverse transcriptase (TERT) and an RNA template (TR), which provides the sequence used to add repetitive nucleotides to the telomere ends. In most somatic cells, telomerase activity is low or absent, which leads to progressive telomere shortening over successive rounds of cell division. However, in germ cells, stem cells, and many cancer cells, telomerase activity is elevated or reactivated, enabling these cells to maintain their telomere length and continue dividing beyond the normal cellular lifespan. This reactivation of telomerase is a key factor in the immortality of cancer cells. Telomerase is crucial for maintaining genomic stability, and its dysfunction can contribute to various diseases, including telomere biology disorders and certain cancers.
