How is DNA packaged within Eukaryotic Cell nucleosomes

DNA is wrapped around proteins called histones, to form nucleosomes. Each nucleosome is a histone octomer composed of (H2A, H2B, H3, and H4) subunits with a 1.65 helical turn of 147 nucleotide bases. Nucleosomes then fold upon themselves to form chromatin. 

Loosely packed Chromatin called euchromatin is assoicated with high gene expression whereas densely packed chromatin called heterochromatin is associated with transcriptional repression (gene silencing). 

During metaphase stage of mitosis and meiosis chromatin becomes supercoilded resulting in the ability to see chromosomes under a microscrope. This is essential for the seperation of DNA between daughter cells. 

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