DNA Structure, Function, And Replication In Biology Practice Test

Telomeres act like protective caps at chromosome ends, and their length limits how many times a cell can divide. In germ cells and many stem cells, telomerase is active, so these cells can add back telomere repeats each time they divide. This keeps telomeres long enough to support many rounds of division, which is essential for producing gametes and for tissue renewal in the body. In contrast, most somatic cells repress telomerase, so with each division telomeres shorten. Over time this leads to a limit on cell divisions, contributing to aging and reduced regenerative capacity. Some cancers reactivate telomerase, enabling continued division. The idea that telomerase is active in all somatic cells to prevent aging isn’t accurate, and the notion that it’s only in bacteria doesn’t match how eukaryotic telomere maintenance works.