Telomeres have been shown to have unique structures that include short nucleotide sequences present as tandemly repeated units. The basic repeat sequence in all the species studied has the pattern 5′−T1−4,A0−1G1−8−3′. Same repeated sequence is found at the end of all chromosomes in a species. Not only this, same telomeres sequence may occur in widely divergent species (eg, Human beings, Neurospora and some acellular slime moulds).
Clusters of G residues in one strand and C residues in the other characterise telomeric DNA. Also, in some species the telomeres terminate with a single-stranded DNA (12−16 nucleotides long) rich in guanine.