What does telomerase do in DNA replication?

Telomerase plays a critical role in DNA replication by adding repetitive nucleotide sequences to the ends of chromosomes, called telomeres, to counteract their natural shortening. During DNA replication, the replication machinery is unable to fully replicate the very ends of linear chromosomes, leading to the loss of a small portion of the telomere with each cell division. Telomerase extends the telomeres by adding more repeats of the DNA sequence (e.g., TTAGGG in humans), effectively maintaining the length of the telomeres and allowing cells to divide more times before reaching the point of critical telomere shortening.