Question

A nucleosome along with linker DNA consists of

• A. Eight molecules of histones and 146 base pairs
• B. Eight molecules of histones and 200 base pairs
• C. Nine molecules of histones and 146 base pairs
• D. Nine molecules of histones and 200 base pairs

Answer 1

The correct option is D Nine molecules of histones and 200 base pairs

• Nucleosomes appear as a “beads-on-a-string” arrangement. Here beads represent complexes of histones and DNA.
• Each bead contains eight histone molecules: two copies each of H${}_2$A, H${}_2$B, H${}_3$, and H${}_4$, out of 200 bp DNA, 146 bp DNA is bound tightly around the histone core and the remainder serve as linker DNA between nucleosomal beads.
• The H${}_1$ histone is associated with the linker DNA to pack adjacent nucleosomes together. Each nucleosome has a total of 9 histones and 200 bp DNA.

So, the correct answer is option D.