Telomeres are specialized structures found at the end of linear, eukaryotic chromosomes.
They are essential for chromosome stability and are sites of recombination events and transcriptional silencing. They also appear to participate in chromosome association and organization. Chromosomes lose a small amount of telomeric DNA after each cell replication because of an inability to replicate the 5' terminus of the DNA strand. It is believed that once telomeres shorten below a critical level they lose their capacity to provide an adequate cap to the chromosome end. This activates a DNA damage response pathway that induces cell cycle arrest.