How does telomerase help prevent telomeres from becoming too short?

Telomerase is a ribonucleoprotein enzyme that helps prevent telomeres—the protective DNA segments at the ends of chromosomes—from becoming too short during cell replication.12

Normally, telomeres shorten with each round of cell division because the replication machinery cannot fully copy the ends of the linear DNA strands. Telomerase counteracts this process by acting as a reverse transcriptase that wraps around the chromosome end and attaches complementary nucleotide repeat sequences to the telomere.1

By extending these repeat sequences, telomerase effectively adds length to the chromosome ends, which allows cells to escape senescence and maintain their ability to divide. While this activity is essential for the function of germ cells and embryonic tissues, it is also a mechanism that cancer cells often exploit to achieve immortality and facilitate unregulated replication.12