Question

If a piece of chromatin contained 200 copies of the histone H4, then how many nucleosomes would be present?

a. 100
b. 200
c. 400
d. We cannot say: nucleosome structures are randomly placed throughout chromatin.

Answer 1

Each nucleosome requires two copies of histone H₄, so with 200 copies of H₄, there would be 100 nucleosomes present in the chromatin.

So, the correct answer to the question is A.

Step-by-step explanation:

To determine how many nucleosomes are present in a piece of chromatin that contains 200 copies of the histone H₄, we must understand the composition of nucleosomes.

A nucleosome is the basic structural unit of chromatin, and it is made up of a segment of DNA wound around a core of histone proteins. This core is an octamer, which consists of eight histone proteins: two copies each of H₂A, H₂B, H₃, and H₄.

Therefore, for each nucleosome, there are two copies of H₄ histones.

Given that we have 200 copies of the H₄ histone, we can calculate the number of nucleosomes by dividing the total number of H₄ histones by the number of H₄ histones per nucleosome.

Since we know each nucleosome must contain two copies of the H₄ histone, we divide the total number of H₄ copies (200) by 2 to find the number of nucleosomes:

nucleosomes = 200 / 2 = 100

Therefore, the correct answer to the question is A) 100.