Telomeres and Replication: Part 4

If chromosome ends contained genes, their coding sequences would erode with each cell division, causing mutations. The protective strategy that has evolved is to place noncoding DNA repeat sequences, telomeric repeats, at the ends of chromosomes. The human noncoding repeat sequence is TTAGGG. During each cell division, the telomeric repeat—not important gene sequences—shortens.

A large blue chromosome shape showing the noncoding repeat sequence of T-T-A-G-G-G at the chromosome ends.