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. *Cell*doi: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 USA*doi: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 USA*doi:10.1073/pnas.85.18.6622