Question

DNA within the cell is wrapped around nucleosomes to form chromatin. When chromatin is in the form of a 30 nm fibril, how many copies of H1 and H2A histone proteins would be found in a stretch of chromatin containing 20 nucleosomes?
a. 40 H1, 20 H2A
b. 20 H1, 40 H2A
c. 40 H1, 40 H2A
d. 10 H1, 30 H2A
e. 20 H1, 20 H2A

Answer 1

Answer:

The correct answer is option b. "20 H1, 40 H2A".

Explanation:

Chromatin is a complex that protects and condenses the genetic material comprised of DNA and proteins. When chromatin is in the form of a 30 nm fibril, nucleosomes have a regular positioning along the DNA. This means that each nucleosome is associated with a single H1 molecule. Therefore a chromatin containing 20 nucleosomes will have 20 copies of H1 and 40 copies of H2A, because each nucleosome has 2 copies of the core histone H2A.