Draw a neat diagram of a nucleosome and label the following: (i) H1 histone (ii) DNA (iii) Octamer

Answer:

[Figure: Nucleosome — a bead-like histone core (octamer of two each of H2A, H2B, H3 and H4) around which the DNA double helix is wound about 1¾ turns (about 146–200 bp); the H1 histone sits on the outside where DNA enters and leaves the core; linker DNA joins adjacent nucleosomes.]

Labels to be shown: (i) H1 histone — on the surface of the bead, sealing the DNA; (ii) DNA — negatively charged double helix wrapped around the core and continuing as linker DNA; (iii) Octamer — positively charged core of eight histone molecules.