Heterochromatin is a tightly packed form of DNA, which comes in multiple varieties. These varieties lie on a continuum between the two extremes of constitutive and facultative heterochromatin. Both play a role in the expression of genes. Because it is tightly packed, it was thought to be inaccessible to polymerases and therefore not transcribed, however according to Volpe et al. (2002), and many other papers since, much of this DNA is in fact transcribed, but it is continuously turned over via RNA-induced transcriptional silencing (RITS). Constitutive heterochromatin can affect the genes near itself...

In anatomy, heterochromia (ancient Greek: ἕτερος, héteros, different + χρώμα, chróma, color) is a difference in coloration, usually of the iris but also of hair or skin. Heterochromia is a result of the relative excess or lack of melanin (a pigment). It may be inherited, or caused by genetic mosaicism, chimerism, disease, or injury. Heterochromia of the eye (heterochromia iridis or heterochromia iridum) is of three kinds. In complete heterochromia, one iris is a different color from the other. In sectoral heterochromia, part of one iris is a different color from its remainder and finally in "central...

Constitutive heterochromatin domains are regions of DNA found throughout the chromosomes of eukaryotes. The majority of constitutive heterochromatin is found at the pericentromeric regions of chromosomes, but is also found at the telomeres and throughout the chromosomes. In humans there is significantly more constitutive heterochromatin found on chromosomes 1, 9, 16, 19 and Y. Constitutive heterochromatin is composed mainly of high copy number tandem repeats known as satellite repeats, minisatellite and microsatellite repeats, and transposon repeats. In humans these regions account for about 200Mb...

In anatomy, heterochromia (ancient Greek: ἕτερος, héteros, different + χρώμα, chróma, color) is a difference in coloration, usually of the iris but also of hair or skin. Heterochromia is a result of the relative excess or lack of melanin (a pigment). It may be inherited, or caused by genetic mosaicism, chimerism, disease, or injury. Heterochromia of the eye (heterochromia iridis or heterochromia iridum) is of three kinds. In complete heterochromia, one iris is a different color from the other. In sectoral heterochromia, part of one iris is a different color from its remainder and finally in "central...

A federal republic is a federation of states with a republican form of government. At its core, the literal meaning of the word republic when used to reference a form of government means: "a country that is governed by elected representatives and by an elected leader (such as a president) rather than by a king or queen". In a federal republic, there is a division of powers between the federal government, and the government of the individual subdivisions. While each federal republic manages this division of powers differently, common matters relating to security and defense, and monetary policy...

Deaf white cats are domestic cats with a pure white coat. Some all-white cats suffer from congenital deafness caused by a degeneration of the inner ear. This condition can occur in cats with yellow, green and blue irises, although the chances of deafness are dramatically increased with blue irises. In white cats with mixed-coloured eyes (odd-eyed cats), it has been found that deafness is more likely to affect the ear on the blue-eyed side. White cats can have blue, gold, green, or copper coloured odd eyes. In one 1997 study of white cats with varying degrees of hearing deficiency, 72% of the animals...