Telomere: The end of a chromosome. The ends of chromosomes are specialized structures that are involved in the replication and stability of DNA molecules. A telomere is a length of DNA that is made up of a repeating sequence of six nucleotide bases (TTAGGG). Small numbers of these terminal TTAGGG sequences are lost from the tips of the chromosomes, but the addition of TTAGGG repeats by the enzyme telomerase compensates for this loss.
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