Question

What are the structures called that give an appearance as 'beads on string' in the chromosomes when viewed under electron microscope ?

Answer 1

Nucleosomes appear as 'beads-on-string' in the chromosomes under electron microscope. Nucleosome is sub-microscopic sub-unit of chromatin which is formed by wrapping of DNA over a core of histone proteins. ... It is oblate structure with a length of 10 nm and a thickness of 5-5.7 nm. Its core is called nu-body.

Answer 2

The structures which appeared as beads on string in the chromosomes are Nucleosomes.

Nucleosomes- The negatively charged DNA is wrapped around the positively charged histone octane to form a structure called Nucleosome.