With so many potential partners, the probes quickly find DNA fragments and reannealing occurs quickly. Most of the fast reannealing DNA is not transcribed. Some may assist in spindle fiber attachment during mitosis. In guinea pigs, highly repetitive sequences are found in the centromere region and may help stabilize the chromosome. Moderately reannealing DNA represents moderately repetitive DNA sequences.
Telomeres help maintain chromosome integrity.
With each cell division and associated mitotic event some of the telomere on each chromosome end is lost. As more divisions occur over time, the chromosomes become less stable and the processes of aging become apparent. This was part of the reason that the cloned sheep Dolly did not live very long. Their existence was first proposed by Barbara McLintock. The functions of most transposons are unknown.