The structure in chromatin seen as 'beads-on' string' when viewed under electron microscope are called

Options

A. Genes
B. Nucleotides
C. Nucleosomes
D. Base pairs

Answer

C

Explanation

Nucleosome appear as "beads - on - string" in the chromosones. Nucleosome is sub - microscopic sub - unit of chromatin which is formed by wrapping of DNA over a core of histone proteins . The term was coined by Ouder , et , al [1975] . It is oblate structure with a length of 10 nm and a thickness of 5-5.7 nm. its core is called nu - body . the latter is formed of four pairs of histone molecules - `H_(2)A,H_(2)B,H_(3)andH_(4)`. DNA makes 1.75 turns over the octamer to form a nucleosome.
Two adjacent nucleosomes are connected by a short segment of unbound DNA called linker DNA . A fifth type of histone called `H_(1)` is attached over the linker DNA.