Some fine sequences are included in more than one class, so the classification listed is not intended to be completely separate.
This is succeeded by an extensive subtelomeric region consisting of various types and lengths of repeats - the telomere associated sequences (TAS).
The subtelomeric repeats can rescue chromosome ends when telomerase fails, buffer subtelomerically located genes against transcriptional silencing and protect the genome from deleterious rearrangements due to ectopic recombination.
They may also be involved in fillers for increasing chromosome size to some minimum threshold level necessary for chromosome stability; act as barriers against transcriptional silencing; provide a location for the adaptive amplification of genes; and be involved in secondary mechanism of telomere maintenance via recombination when telomerase activity is absent.
Regions of the genome with protein-coding genes include several elements: Many regions of the DNA are transcribed with RNA as the functional form: Other RNAs are transcribed and not translated, but have undiscovered functions.