 Both centromeres and telomeres are heterochromatic, as is the Barr body of the second, inactivated X-chromosome in a female.Heterochromatin has been associated with several functions, from gene regulation to the protection of chromosome integrity; some of these roles can be attributed to the dense packing of DNA, which makes it less accessible to protein factors that usually bind DNA or its associated factors.For example, naked double-stranded DNA ends would usually be interpreted by the cell as damaged or viral DNA, triggering cell cycle arrest, DNA repair or destruction of the fragment, such as by endonucleases in bacteria.