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The precise structure of the chromatin fiber in the cell is not known in detail. [10] This level of chromatin structure is thought to be the form of heterochromatin, which contains mostly transcriptionally silent genes. Electron microscopy studies have demonstrated that the 30 nm fiber is highly dynamic such that it unfolds into a 10 nm fiber ...
The four H3 and H4 subunits form a tightly packed tetramer that associates with two H2A/H2B dimers to form each octamer. About 147 bp of DNA is wrapped around the octamer to form a nucleosome. Nucleosomes can be arrayed in the loosely packed beads-on-a-string form of chromatin, but are generally more tightly packaged into the 30-nm fiber.
S/MAR-functions: constitutive and facultative. A chromatin domain with constitutive S/MARs at its termini (I). When functional demands require the specific translocation of the constituent gene to the matrix, facultative S/MARs responds to topological changes which are initiated by the association of transcription factors (TF) and supported by histone acetylation.
Basic units of chromatin structure. Histone H2B is a structural protein that helps organize eukaryotic DNA. [5] It plays an important role in the biology of the nucleus where it is involved in the packaging and maintaining of chromosomes, [5] regulation of transcription, and replication and repair of DNA. [2]
The solenoid structure can increase this to be 40 times smaller. [2] When DNA is compacted into the solenoid structure can still be transcriptionally active in certain areas. [7] It is the secondary chromatin structure that is important for this transcriptional repression as in vivo active genes are assembled in large tertiary chromatin ...
Eukaryotic chromosome structure refers to the levels of packaging from raw DNA molecules to the chromosomal structures seen during metaphase in mitosis or meiosis. Chromosomes contain long strands of DNA containing genetic information. Compared to prokaryotic chromosomes, eukaryotic chromosomes are much larger in size and are linear chromosomes.
In biology, the chromosome scaffold is the backbone that supports the structure of the chromosomes. It is composed of a group of non-histone proteins that are essential in the structure and maintenance of eukaryotic chromosomes throughout the cell cycle. These scaffold proteins are responsible for the condensation of chromatin during mitosis. [1]
Promoter chromatin signature: The H3K4me3 modification is related with transcriptional activity. This modification takes place in adjacent nucleosome to the transcription start site (TSS), relaxing the chromatin structure. This histone modification is used as a marker of promoters, using it to map these elements in the human genome.