How does telomerase function in relation to telomeres?

Telomerase is an enzyme that plays a critical role in maintaining the length and integrity of telomeres, which are repetitive DNA sequences located at the ends of chromosomes. When cells divide, the conventional DNA replication process cannot fully replicate the ends of linear chromosomes, leading to gradual shortening of telomeres over successive rounds of cell division. This shortening is associated with cellular aging and limits the number of times a cell can divide.

The specific function of telomerase involves adding nucleotide sequences to the telomeres to counteract this shortening. Telomerase contains a short RNA template that is complementary to the G-rich strand of the telomere. During the elongation process, telomerase uses this RNA template to synthesize new DNA repeats, thus extending the telomeres and allowing the chromosome to be fully replicated during cell division.

In contrast, the other choices do not accurately describe the function of telomerase. The enzyme does not degrade telomeres, replace DNA segments, nor directly prevent degradation; instead, it replenishes telomere length, thus helping to maintain chromosome stability and cellular longevity. This understanding of telomerase helps clarify its crucial role in cellular mechanisms, particularly in stem cells, germ cells, and certain cancerous cells