The cell is the basic building block of life and the nucleus is the control unit of the cell.

The nucleus was discovered by Robert Brown.

Most cells have one nucleus, but certain cells, such as the red blood cells found in the blood, do not have a nucleus.

Some cells have more than one nucleus, for example, the paramecium is a unicellular organism that has more than one nucleus.

In prokaryotes, for e.g. bacteria, there is no nucleus, but a nuclear body instead. The cell has a loop of DNA and no chromatin proteins.

In eukaryotes, the nucleus is surrounded by the nuclear envelope, which is a double-layered structure composed of lipids and proteins. The nuclear envelope separates the nucleoplasm from the cell cytoplasm. It has pores lined with the pore complex to regulate the influx and efflux of the protein, the RNA and other macromolecules.

The nucleus contains the hereditary material, which is in the form of an uncoiled structure called chromatin network. This network contains the DNA and the proteins. At the start of cell division, the protein coils up, condensing the chromatin network and forms a rod-shaped body called the chromosome. At this stage the chromosome first becomes visible.

The nucleus plays an important role in cell division. During cell division, the cell divides into two, and the genetic information is transferred from the parent generation to the next generation with the division of the chromosomes.

The nucleus contains a small body called the nucleoli, which plays an important role in the synthesis of RNA.