Question

Study the diagram given below and answer the questions that follows:

(a) Identify the structure shown in the above figure.
(b) Identify the labels P and Q. 
(c) Write the nature of histone proteins. 
(d) Distinguish between Euchromatin and Heterochromatin.

Hint:

Nucleosomes help compact DNA and regulate gene expression. Euchromatin is loosely packed and active, whereas heterochromatin is tightly packed and inactive.

Answer 1

Step 1 (a): The structure shown in the figure is a **nucleosome**, the fundamental unit of chromatin packaging in eukaryotes.

Step 2 (b):
Label P – DNA strand 
Label Q – Histone core (octamer of histone proteins)

Step 3 (c): Histone proteins are **basic** in nature due to the abundance of positively charged amino acids (like lysine and arginine) which bind to the negatively charged DNA. 

Step 4 (d):