A structure of noncoding DNA (DNA that does not convey genetic instruction) at each end of a CHROMOSOME. Telomeres are essential for chromosome duplication during cell division. They function as handles to pull the chromatids (dividing chromosomes) apart as the mother cell divides into the two new daughter cells.
The process of cell division permanently destroys a tiny fragment of the telomere, however. Eventually the telomere becomes too short to participate in chromosome duplication, and the cell stops dividing. Researchers believe the shortening of telomeres is key to APOPTOSIS, the apparently programmed death of cells. In cancer cells the telomeres regenerate after cell division, which researchers believe is one of the factors that allows cancer cells to grow uninhibited.
For further discussion of telomeres within the context of the structures and functions of genetics, please see the overview section “Genetics and Molecular Medicine.”