Question

Find out the number of nucleosomes present in a human cell.

• A. 16.50 billion
• B. 33 million
• C. 200 million
• D. 16.50 million

Answer 1

The correct option is B 33 million

Introduction to nucleosomes
Nucleosomes are submicroscopic units of chromatin which are about 11nm in diameter and 5.7-6$nm$ in height. Each nucleosome consists of a core of 8 histone molecules around which the DNA strand is tightly wrapped in 2 circles. A typical nucleosome consists of 200 base pairs of DNA.


Number of nucleosomes in human cell
The DNA in a human cell consists of 6.6 x109 bp
We know that 200 bp forms = 1 nucleosome
Thus, 1 bp forms = 1/200 nucleosomes
Hence, $6.6\times 109bp$ will form$=\left(1x6.6x109\right)/200$ nucleosomes $=3.3x107$ nucleosomes $=33x106$ nucleosomes = 33 million nucleosomes.
Final answer
(C) 33 million