What are two things that happen to telomeres as cells undergo cell divisions?

As cells undergo division, telomeres, which are protective caps at the ends of chromosomes, shorten with each division. This gradual shortening is a result of the inability of DNA replication machinery to fully replicate the ends of linear chromosomes. Eventually, when telomeres become critically short, it triggers cellular senescence or apoptosis, limiting the number of times a cell can divide. This process is thought to be a contributing factor to aging and the lifespan of cells.