∞ generated and posted on 2016.08.28 ∞

Chromosome end sequence as found in the cells of eukaryotes.

The telomeres, as laid down by the enzyme, telomerase, protect the ends of the linear eukaryotic chromosomes from eroding in the course of DNA replication. The reason for the concern has to do with an inability to lay down RNA primer at the immediate ends of double helices, which precludes the duplication of those ends.

With each round of replication, these chromosomes thus get shorter and by having telomeres not only is this shortening occurring within nonessential DNA but the telomeres, at least in some cells, can be enzymatically lengthened.

For a cell line to become immortal, such as one sees with tumor and cancer cells, it is essential that those cells produce telomerase. Otherwise telomere erosion will place strong limits on how much chromosome replication can be achieved prior to the loss of DNA that is essential to ongoing cell functioning.