Every single cell in our body has 46 chromosomes that if attached together would make a very thin but about 2 m long str

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Every Single Cell In Our Body Has 46 Chromosomes That If Attached Together Would Make A Very Thin But About 2 M Long Str 1 (45.32 KiB) Viewed 13 times

Every single cell in our body has 46 chromosomes that if attached together would make a very thin but about 2 m long string of DNA [1]. To be able to fit this DNA into the volume of a human cell nucleus that has average diameter of 10 µm the DNA must be organized in high-order nucleoprotein complex - chromatin [1]. In the chromatin the DNA is wrapped around nucleosomes that consists of two molecules of each core histones - H2A, H2B, H3, and H4. With the help of the fifth linker H1 histone they establish and maintain the chromatin structure and function [2]. The chromatin organization prevents enzymes and proteins like transcriptional factors, replication factors, and repair enzymes to access the DNA. To regulate the access to the DNA the cells are employing different mechanisms, including changes in the histone composition, histone post-translational modifications, nucleosome occupancy and positioning within chromatin and many others [3]. Search in the literature and find examples of specific epigenetic mechanism(s) involved in regulation of your favorite process - expression of particular gene in particular type of cells, regulation of DNA repair in particular context, maintain stemness in pluripotent cells, etc., the possible examples are enormous.