Describe the structure of nucleus.

Explanation

Nucleus is also called as cell brain. Nucleus was first described by Robert Brown. The interphase nucleus has highly extended and elaborate nucleo protein fibres called chromatin, nuclear matrix and one or more spherical bodies called nucleoli. Electron microscopic has revealed that the nucleus surrounded by two parallel membranes with a space between called the perinuclear space. The outer membrane usually remains continuous with the endoplasmic reticulum. At a number of places the nuclear envelope is interrupted by minute pores. These nuclear pores are the passages through which movement of RNA and protein molecules in both directions between the nucleus and the cytoplasm. The nucleoplasm contains nucleolus and chromatin. Chromatin contains DNA and some, basic proteins called histones. Some non-histone proteins and also RNA. During the cell division time cell shows chromosomes in the nucleus.