Question

With the help of a suitable diagram describe the structure of a nucleosome.

Answer 1

In eukaryotes, DNA is packaged in association with some basic proteins known as histone proteins rich in basic amino acids lysine and arginine. There are five types of histone proteins: H1, H2A, H2B, H3, H4.

Four of these histones H2A, H2B, H3, H4 occur in a pair to form a histone octamer or the core of nucleosome. Around this histone octamer is wrapped about 166 bp of DNA. This structure formed by the negatively charged DNA wrapped around the positively charged histone octamer (the core particle) is called nucleosome.

The DNA connecting the two adjacent nucleosomes is called the linker DNA. It bears the H1 histone which connects one core particle with the other.