Chromatin

The chromatin can be found in the cell’s nucleus. It is the combination between DNA and different proteins, the histones. Histones H2A, H2B, H3 and H4 attach each other to form an octamer or nucleosome, meanwhile the histone H1 attaches to the adjacent nucleosomes “condensing” the DNA and forming the chromosomes – this happens during prophase in which chromatin becomes coiled into chromosomes and each chromosome has two chromatids. Chromatin’s functions are to package DNA into a smaller volume so it can fit in the cell, it allows to have a higher control over these genes' expression.

 It’s called Euchromatin when DNA wraps around histone proteins to form the nucleossomes and it corresponds to a lightly packed form of chromatin . When multiple histones wrap into a 30 nm fibre, consisting in chromatin most compact form, it’s called heterochromatin, which can be constitutive or facultative. 

G4.2