In this article we will discuss about the structure of nucleus. This will also help you to draw the structure and diagram of nucleus.
1. It was discovered by Robert Brown (1831).
2. It is the major part of a eukaryotic cell that contains the genetic material. Prokaryotic cells have no nucleus as such.
3. Each nucleus remains enclosed in a nuclear membrane or nuclear envelope. It is a double membrane surrounding the nucleus (Fig. 299). Each layer has a typical plasma-membrane like structure and is 4 nm to 6 nm in width.
Electron micrographs reveal the connection between the outer nuclear membrane and the endoplasmic reticulum. A perinuclear space is present in between the membranes. At various points the two membranes fuse and form pores.
4. The interphase nucleus of eukaryotic cells contains a network of chromatin fibres, which become organised into chromosomes before cell division.
5. The substance of the nucleus apart from the chromatin is called nucleoplasm or karyoplasm. It contains complexes and enzymes necessary for DNA replication and synthesis of RNA molecules.
6. One or more nucleoli are also present in the nucleus. A nucleolus consists of proteins associated with RNA. In the electron micrographs, a nucleolus shows a central area of short fibers surrounded by a matrix of protein material with several granules embedded in the peripheral region.
7. Nucleus controls all the genetic activities of the cell. In the germ cells it carries hereditary information from generation to generations.