Telomere
DETelomer
Telomeres are the protective caps on the ends of your chromosomes, a bit like the plastic tips on shoelaces. They are made of a short DNA sequence (TTAGGG) repeated over and over, and they stop the chromosome ends from fraying, fusing, or getting mistaken for damage. Here is the catch: every time a cell divides, its telomeres get a little shorter, because the copying machinery (DNA polymerase) cannot quite finish the very ends. When they get critically short, the cell stops dividing (senescence) or self-destructs (apoptosis). Telomere shortening is one of the twelve hallmarks of aging and is linked to heart disease, a weaker immune system, and slower tissue repair.
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Sources
- Greider CW, Blackburn EH. (1985). Identification of a specific telomere terminal transferase activity in Tetrahymena extracts. Celldoi:10.1016/0092-8674(85)90170-9
- Epel ES, Blackburn EH, Lin J, Dhabhar FS, Adler NE, Morrow JD, Cawthon RM. (2004). Accelerated telomere shortening in response to life stress. Proceedings of the National Academy of Sciences USAdoi:10.1073/pnas.0407162101
- Moyzis RK, Buckingham JM, Cram LS, Dani M, Deaven LL, Jones MD, Meyne J, Ratliff RL, Wu JR. (1988). A highly conserved repetitive DNA sequence, (TTAGGG)n, present at the telomeres of human chromosomes. Proceedings of the National Academy of Sciences USAdoi:10.1073/pnas.85.18.6622