How is nucleosome formed? Draw a diagram of the nucleosome.

Explanation

In eukaryotes, the DNA is wrapped around positively charged histone octamer into structure called nucleosome.
• A typical nucleosome consists of 200 bp of DNA helix.
• The nucleosomes are the repeating units that form chromatin fibres.
• The chromatin fibres condense at metaphase stage of cell division to form chromosomes.
• The packaging of chromatin at higher level requires additional set of proteins called non_xFFFE_histone chromosomal (NHC) proteins.
• In a nucleus, certain regions of the chromatin are loosely packed and they stain lighter than the other regions, these are called euchromatin.
• The other regions are tightly packed and they stain darker and are called heterochromatin.
• Euchromatin is transcriptionally more active than heterochromatin.