Telomeres are the physical ends of linear eukaryotic chromosomes. They are specialized nucleoprotein complexes that have important functions, primarily in the protection, replication, and stabilization of the chromosome ends. In most organisms studied, telomeres contain lengthy stretches of tandemly repeated simple DNA sequences composed of a G- rich strand and a C-rich strand (called terminal repeats). These terminal repeats are highly conserved; in fact all vertebrates appear to have the same simple sequence repeat in telomeres: (TTAGGG)n. Often sequences adjacent to the telomeric repeats are highly polymorphic, are rich in DNA repetitive elements (termed subtelomeric repeats), and in some cases, genes have been found in the proterminal regions of chromosomes.

Structure and function of telomere:

The telomere is a "ribonucleoprotein complex" composed of a protein component and an RNA primer sequence which acts to protect the terminal ends of chromosomes. This prevents chromosomal fraying and prevents the ends of the chromosome from being processed as a double strand DNA break, which could lead to chromosome-to-chromosome telomere fusions.