Describe the structure of nucleus.

Explanation

Nucleus : It was first discovered by Robert Brown. Later the material of the nucleus stained by the basic dyes was given the name chromatin by Flaming. The interphase nucleus has highly extended and elaborate nucleoprotein fibres called chromatin, nuclear matrix and one or two nucleoli. Electron microscopy has revealed that the nucleus is covered by double lavered nuclear envelope, with a Space between called perinuclear space, forms a barrier between materials present inside the nucleus and the cytoplasm.
The outer nuclear envelope remains. continuous with the endoplasmic reticulum and also bears ribosomes. At a number of places, the nuclear envelope is interrupted by nuclear pores, which allows the passage of RNA and protein molecules in both directions between the nucleus and cytoplasm. The nucleoplasm contains nucleolus and chromatin. The nucleoli and spherical structures, involved in active ribosomal RNA synthesis. The chromatin, in different stages of cell division, become chromosomes. They contain DNA and some basic proteins cailed histones and also RNA. Nucleus plays an important role in biogensis of ribosomes. It plays a significant role in mitosis.