Of all the challenges that come with a diagnosis of autism spectrum disorder (ASD), the social difficulties are among the most devastating. Currently, there is no treatment for this primary symptom of ASD. New research at ...
Mar 12, 2018
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Gene editing may be a potential treatment for anxiety and alcohol use disorder in adults who were exposed to binge drinking in their adolescence, according to the results of an animal study published in the journal Science ...
May 4, 2022
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When the brain forms a memory of a new experience, neurons called engram cells encode the details of the memory and are later reactivated whenever we recall it. A new MIT study reveals that this process is controlled by large-scale ...
Oct 5, 2020
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(Medical Xpress)—One way cells promote tumor suppression is through a process called senescence, an irreversible arrest of proliferation. Senescence is thought to be associated with normal aging, but is also a protective ...
Aug 30, 2013
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Each face is unique, even though the genes controlling facial shape are almost identical in every individual. Filippo Rijli and his team at the Friedrich Miescher Institute for Biomedical Research (FMI) have discovered an ...
Mar 30, 2017
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A newly described form of stress called chromatin architectural defect, or chromatin stress, triggers in cells a response that leads to a longer life. Researchers at Baylor College of Medicine and the Houston Methodist Research ...
Jul 10, 2019
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Northwestern Engineering's Vadim Backman has developed an effective new strategy for treating cancer, which has wiped out the disease to near completion in cellular cultures in the laboratory.
Nov 6, 2017
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A study led by the research center of Genentech in South San Francisco, published in Cell Genomics, has looked for drug targets that could address age-related macular degeneration (AMD), a condition at the center of vision ...
In a finding that could help lead to new therapies for immune diseases like multiple sclerosis and IBD, scientists report in the Journal of Experimental Medicine identifying a gene and family of proteins critical to the formation ...
Oct 25, 2019
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Scientists at Johns Hopkins Medicine have found types of cells in the brain that are most susceptible to inherited genetic variants linked to schizophrenia. As a result, their work reveals a shortlist of the variants that ...
Jul 3, 2020
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Chromatin is the combination of DNA and proteins that make up the contents of the nucleus of a cell. The primary functions of chromatin are; to package DNA into a smaller volume to fit in the cell, to strengthen the DNA to allow mitosis and meiosis and prevent DNA damage, and to control gene expression and DNA replication. The primary protein components of chromatin are histones that compact the DNA. Chromatin is only found in eukaryotic cells: prokaryotic cells have a very different organization of their DNA which is referred to as a genophore (a chromosome without chromatin).
The structure of chromatin depends on several factors. The overall structure depends on the stage of the cell cycle: during interphase the chromatin is structurally loose to allow access to RNA and DNA polymerases that transcribe and replicate the DNA. The local structure of chromatin during interphase depends on the genes present on the DNA: DNA coding genes that are actively transcribed ("turned on") are more loosely packaged and are found associated with RNA polymerases (referred to as euchromatin) while DNA coding inactive genes ("turned off") are found associated with structural proteins and are more tightly packaged (heterochromatin). Epigenetic chemical modification of the structural proteins in chromatin also alter the local chromatin structure, in particular chemical modifications of histone proteins by methylation and acetylation. As the cell prepares to divide, i.e. enters mitosis or meiosis, the chromatin packages more tightly to facilitate segregation of the chromosomes during anaphase. During this stage of the cell cycle this makes the individual chromosomes in many cells visible by optical microscope.
In general terms, there are three levels of chromatin organization:
There are, however, many of cells which do not follow this organisation. For example spermatozoa and avian red blood cells have more tightly packed chromatin than most eukaryotic cells and trypanosomatid protazoa do not condense their chromatin into visible chromosomes for mitosis.
This text uses material from Wikipedia, licensed under CC BY-SA
