Heterochromatin and Euchromatin

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by Marlo25
Last updated 5 years ago

Cell Biology

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Heterochromatin and Euchromatin

Heterochromatin and Euchromatin

In a nucleus on interphase, most of the chromatin it is in relatively non-condensed euchromatin shape and distributed throughout the core. The structure of euchromatin is a chain of an unfolded nucleosomes, each one consist of eight proteins known as histones with approximately 147 base pairs of DNA wound around them. Its genes are active so it participates in transcription of DNA to mRNA products. The unfolded structure allows gene regulatory proteins and RNA polymerase complexes to bind to the DNA sequence, which can then initiate the transcription process. In prokaryotes euchromatin is the only form of chromatin present.

Johann Heinrich Emil Heitz was born on October 29, 1892 in Strasbourg and died on July 8, 1965 in Lugano. He studied botany at the University of Hamburg and was a pioneer of botanical and zoological cytogenetics. In 1928 he differed in images of mosses the length of chromosomes, that differed in chromatin, heterochromatin and euchromatin. In 1955, he was the first winner of the Schleiden Medal.


Heterochromatin is usually localized on the periphery of the nucleus. It consists of genetically inactive satellite sequences; centromeres and telomeres are heterochromatics. It remains condensed during interphase and inactive for transcription and gene expression, is for that reason transcriptionally inactive. It has several functions from the gene regulation to the protection of chromosome integrity, also encoding proteins and enzymes such as ribosomal protein and the kinase. There are two types:Constitutive: identical for all cells in the body and has no genetic information.Facultative: is presented condensed during interphase but not in all stages of development, is differs among cell types and contains information about those genes that are not expressed.


Chromatin is the set of DNA, histones, non-histone proteins and RNA found in the interphase nucleus of eukaryotic cells and constitutes the genome of such cells.




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