Either of the sections of DNA occurring at the extreme ends of each chromosome in a eukaryotic cell. Telomeres consist of highly repetitive sequences of DNA that do not code for proteins, but function as caps to keep chromosomes from fusing together. The length of the telomere influences the stability of genetic information just interior of the telomere, since the nucleotide sequences at the ends of a chromosome are not copied by DNA polymerase. Successive copying can thus shorten telomeres, sometimes to the point that functional genes near the telomeres are lost, and this may play a role in cellular senescence and age-related diseases. In germ cells, stem cells, and some cancer cells, shortened telomeres can be extended by the enzyme telomerase, thus keeping both the telomeres and the genes near them functioning. Most somatic cells do not express telomerase, and the shortening of telomeres during each round of cell division may be part of the natural aging of cells.
telomere
Cultural
The long end sequences of a DNA strand occurring at the tip of the chromosomes; a type of repetitive DNA that usually consists of one hundred to fifteen hundred copies of a single DNA sequence.
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During DNA replication, small parts of the telomere are lost with each cycle. Scientists think that this loss may be related to the aging process.
They also knew that there was a string of DNA at the end of each chromosome called a telomere, which shortened a tiny bit each time a cell divided, like time ticking off a clock.
From
"The Immortal Life of Henrietta Lacks" by Rebecca Skloot
