Telomeres are regions of highly repetitive, non-coding DNA capping the ends of linear eukaryotic chromosomes; because replication enzymes cannot copy the extreme terminus of a linear DNA molecule, these expendable repeats serve as a sacrificial buffer that protects coding sequence from progressive end-loss and also prevents chromosome ends from fusing with one another. Successive rounds of replication shorten telomeres until a cell can no longer divide, unless the enzyme telomerase restores repeat length, linking telomere dynamics to replicative capacity and cellular senescence. The concept sits in molecular genetics and links chromosome structure to the broader classification of genomic DNA by sequence redundancy — single-copy DNA, moderately repetitive DNA, and highly repetitive DNA — which differ systematically in gene content, transcription/translation, and mutation rate.
Telomeres are regions of highly repetitive, non-coding DNA capping the ends of linear eukaryotic chromosomes; because replication enzymes cannot copy the extreme terminus of a linear DNA molecule, th…