What are telomeres commonly referred to as in the context of cell division?

Telomeres are commonly referred to as "cell clocks" because they play a crucial role in regulating the number of times a cell can divide. They are repetitive sequences of DNA located at the ends of linear chromosomes, functioning to protect the chromosome ends from deterioration and from fusion with neighboring chromosomes. Each time a cell divides, a portion of the telomere is lost, which effectively counts down the number of divisions a cell can undergo. When telomeres become critically short, the cell can enter senescence or apoptosis, thus limiting its lifespan. This characteristic gives telomeres their nickname as "cell clocks," emphasizing their role in cellular aging and division limits.