Definitions for heterochromatin
ˌhɛt ər əˈkroʊ mə tɪnhet·e·rochro·matin

WiktionaryRate this definition:0.0 / 0 votes

1. heterochromatinnoun

   Heterochromatic tightly coiled chromosome material; believed to be genetically inactive

WikipediaRate this definition:0.0 / 0 votes

1. Heterochromatin

   Heterochromatin is a tightly packed form of DNA or condensed DNA, which comes in multiple varieties. These varieties lie on a continuum between the two extremes of constitutive heterochromatin 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). Recent studies with electron microscopy and OsO4 staining reveal that the dense packing is not due to the chromatin.Constitutive heterochromatin can affect the genes near itself (e.g. position-effect variegation). It is usually repetitive and forms structural functions such as centromeres or telomeres, in addition to acting as an attractor for other gene-expression or repression signals. Facultative heterochromatin is the result of genes that are silenced through a mechanism such as histone deacetylation or Piwi-interacting RNA (piRNA) through RNAi. It is not repetitive and shares the compact structure of constitutive heterochromatin. However, under specific developmental or environmental signaling cues, it can lose its condensed structure and become transcriptionally active.Heterochromatin has been associated with the di- and tri -methylation of H3K9 in certain portions of the human genome. H3K9me3-related methyltransferases appear to have a pivotal role in modifying heterochromatin during lineage commitment at the onset of organogenesis and in maintaining lineage fidelity.

WikidataRate this definition:0.0 / 0 votes

1. Heterochromatin

   Heterochromatin is a tightly packed form of DNA, which comes in different 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, where constitutive heterochromatin can affect the genes near them and where facultative heterochromatin is the result of genes that are silenced through a mechanism such as histone methylation or siRNA through RNAi. Constitutive heterochromatin is usually repetitive and forms structural functions such as centromeres or telomeres, in addition to acting as an attractor for other gene-expression or repression signals. Facultative heterochromatin is not repetitive and although it shares the compact structure of constitutive heterochromatin, facultative heterochromatin can, under specific developmental or environmental signaling cues, lose its condensed structure and become transcriptionally active. Heterochromatin is often associated with the di and tri-methylation of H3K9.

U.S. National Library of MedicineRate this definition:0.0 / 0 votes

1. Heterochromatin

   The portion of chromosome material that remains condensed and is transcriptionally inactive during INTERPHASE.

How to pronounce heterochromatin?

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How to say heterochromatin in sign language?

Numerology

1. Chaldean Numerology

   The numerical value of heterochromatin in Chaldean Numerology is: 6

2. Pythagorean Numerology

   The numerical value of heterochromatin in Pythagorean Numerology is: 1

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References

1. ^ Wiktionary
   https://en.wiktionary.org/wiki/Heterochromatin
2. ^ Wikipedia
   https://en.wikipedia.org/wiki/Heterochromatin
3. ^ Wikidata
   https://www.wikidata.org/w/index.php?search=heterochromatin