heterochromatin


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heterochromatin

 [het″er-o-kro´mah-tin]
that state of chromatin in which it is dark-staining, genetically inactive, and tightly coiled.
constitutive heterochromatin the chromatin in regions of the chromosomes that are invariably heterochromatic; it contains highly repetitive sequences of DNA that are genetically inactive and serves as a structural element of the chromosome.
facultative heterochromatin the chromatin in regions of the chromosomes that become heterochromatic in certain cells and tissues; for example, it makes up the inactive X chromosome in female somatic cells.

het·er·o·chro·ma·tin

(het'ĕr-ō-krō'mă-tin),
The part of the chromonema that remains tightly coiled and condensed during interphase and thus stains readily.

heterochromatin

/het·ero·chro·ma·tin/ (-kro´mah-tin) that state of chromatin in which it is dark-staining, genetically inactive, and tightly coiled.

heterochromatin

(hĕt′ə-rō-krō′mə-tĭn)
n.
Tightly coiled chromosomal material that stains deeply during interphase and is believed to be genetically inactive.

heterochromatin

[-krō′mətin]
Etymology: Gk, heteros, different, chroma, color
the part of a chromosome that is inactive in gene expression but may function in controlling metabolic activities, transcription, and cell division. It stains most intensely during interphase and usually remains in a condensed state throughout the cell cycle. It consists of two types: constitutive heterochromatin, which is present in all cells and is characteristic of the Y chromosome, and facultative heterochromatin, which is present in the inactivated X chromosome of the mammalian female. Compare euchromatin. See also chromatin. heterochromatic, adj.

het·er·o·chro·ma·tin

(het'ĕr-ō-krō'mă-tin)
The part of the chromonema that remains tightly coiled and condensed during interphase and thus stains readily.

heterochromatin

A length of chromatin in the genome that is permanently highly condensed and whose DNA is not transcribed.

heterochromatin

any chromosomal segments or whole chromosomes that appear darkly stained during interphase of the CELL CYCLE (as compared to EUCHROMATIN) due to tight condensation, which may indicate genetic inactivity. Hetero chromatin may be condensed at all times (constitutive) or only at certain times (facultative). see C-BANDING.

heterochromatin

that state of chromatin in which it is dark-staining, genetically inactive, and tightly coiled.
References in periodicals archive ?
Most interestingly, the researchers discovered that the disruption to heterochromatin caused by the release of dATF-2 was transmitted to the next generation of cells, without any change to their DNA sequences.
The chromatin decondenses, the heterochromatin particles become smaller, and a nucleolus appears.
This analysis has allowed us to identify two very different chromosomal groups and to discuss the role of heterochromatin and genome size variation in the karyologic evolution of T.
C-banding analyses and the evolution of heterochromatin among arvicolid rodents.
The nuclei were round and many were indented, and they featured both prominent nucleoli and small amounts of peripherally located heterochromatin.
While some of the mutations appear to specifically affect heterochromatin formation, other mutations have been found to exhibit partial alleviation of basal repression at the GALl promoter, as well as temperature-sensitive growth.
For example, along the "arms" of certain alfalfa chromosomes scientists identified thick bands of DNA and protein material called heterochromatin.
Most authors have relied on Rb fusions (inbred strains; Davisson and Akeson 1993) or on differences in the quantity of centromeric heterochromatin (inbred strains and Mus spretus; Matsuda and Chapman 1991; Ceci et al.
Methylation of Lysine-9 of Histone H3: Role in Heterochromatin Modulation and Tumorigenesis
Proteomic analysis of embryonic kidney development: Heterochromatin proteins as epigenetic regulators of nephrogenesis.