Explain the structure and functions of nucleus.

Nucleus :

1. The nucleus is the control house of the cell.
2. It is the main distinguishing characteristic feature of eukaryotic cells.
3. It was first discovered and named by Robert Brown in plant cells in 1833.

Structure of nucleus :

1. Nuclear Membrane
2. The nucleus has a double-layered covering called a nuclear membrane which separates the nucleus from the cytoplasm.
3. The outer and the inner nuclear membrane are joined at certain places to form pores which allow the transfer of material from the nucleoplasm to the cytoplasm. It forms about 5 – 15% of the surface area of the nuclear membrane.
4. The space between two nuclear membranes is called perinuclear space

2. Nucleoplasm

1. The nuclear envelope encloses a fibrous, transparent, semi-solid granular substance that fills the nucleus. It includes chromatin fibers and nucleolus and is called nucleoplasm.

3. Nucleolus

1. One or more than one denser body called nucleolus is present inside the nucleus.
2. The nucleolus is attached to a chromatin fiber at a specific region called the nucleolar organizer region.
3. It is non membrane bound organelle.
4. It is called a factory of ribosomes as it is made up of a large amount of RNA (ribonucleic acid) and proteins that are used in the formation of ribosomes.

Functions of the nucleus :

1. The nucleus plays a major role in cell division the process by which a single cell divides and forms two daughter cells.
2. It controls the metabolism of the cell.
3. It controls the process of cell division.
4. It helps in the transmission of hereditary characters from parents to the offspring.
5. Cell reproduction cannot take place without a nucleus.
6. It helps in the regulation of the cell cycle.