Is a repetitive sequence at the end of each human chromosome?

Yes, each human chromosome has a repetitive sequence at its ends called telomeres. These telomeres protect the chromosome from degradation and prevent it from fusing with neighboring chromosomes. As cells divide, telomeres shorten, which is associated with aging and limits the number of times a cell can divide. When telomeres become critically short, the cell may enter a state of senescence or undergo apoptosis.