NEET BIOLOGY

Detailed explanation-1: -The nucleosome core particle represents the first level of chromatin organization and is composed of two copies of each of histones H2A, H2B, H3 and H4, assembled in an octameric core with 146-147 bp of DNA tightly wrapped around it [1, 2].

Detailed explanation-2: -Histones H2A, H2B, H3 and H4 are known as the core histones, and they come together to form one nucleosome. The nucleosome core is formed of two H2A-H2B dimers and a H3-H4 tetramer.

Detailed explanation-3: -Each nucleosome is composed of a little less than two turns of DNA wrapped around a set of eight proteins called histones, which are known as a histone octamer. Each histone octamer is composed of two copies each of the histone proteins H2A, H2B, H3, and H4.

Detailed explanation-4: -Histone H4 is an important protein in the structure and function of chromatin, where its sequence variants and variable modification states are thought to play a role in the dynamic and long term regulation of genes.

Detailed explanation-5: -Each individual nucleosome core particle consists of a complex of eight histone proteins-two molecules each of histones H2A, H2B, H3, and H4-and double-stranded DNA that is 146 nucleotide pairs long.