The lengths of telomere repeats from different cell lines varied, but correlated with the circumferences of the lariat circles in the DNA prepared as above. At their ends, telomeres can assume special structures, the G quartets. G quartets can account for the stability properties of chromosome ends. There is no analogous evidence favoring a biological relevance of G-quartet structures. Telomere sequences have been characterized from many organisms.
Telomere synthesis requires a special enzyme.
DNA damage checkpoints are activated. The fusions occur after replication but are not between sister chromatids because only those DNA ends formed during replication by leading strand synthesis appear to participate in the joining.