Nucleus, Structure and Function of Nucleus in Cell

Nucleus is a spherical and oval cell organelle found in all eukaryotic cells. This organelle is absent in prokaryotic cells. It is highly specialized part of protoplasm. It is denser than cytoplasm. It is located in the center in a young cell while in mature cell it comes to lie on one side. Its size varies between 5 to 25 micrometer. The nucleus is the key importance because it stores the genetic information that determine the characteristics of the body cell and their metabolic function.

Structure of Nucleus

The nucleus is surrounded by a thin membrane known as nuclear membrane or nuclear envelope. The nuclear membrane has small numerous pores that help in direct communication between cytoplasm and the nucleoplasm. In the nucleoplasm enzyme and other complex substances are found which take part in the formation of DNA and RNA. A network of fine thread like structure called chromatin material found in nucleoplasm. The chromatin is the hereditary material. In division of nucleus the chromatin forms a definite number of thread like structures called chromosomes which carry hereditary units on their surface called genes. Chemically chromatin consist genetic material and proteins. One or more globular bodies are present known as nucleolus. At the time of division of nucleus, the nucleoli disappear and new ones are formed in each daughter nucleus.

Functions of Nucleus

The specific functions performed by the nucleus are given:

1. It is regarded as the controlling center of cell. It controls all vital activities of cell. It acts like a brain of cell.

2. It controls or directs the synthesis of enzymes which catalyze most of the reactions in cell.

3. It produce chromosomes during cell division. The chromosomes are responsible to transfer hereditary characters from generation to generation.

4. It directly takes part in cell division and reproduction.

5. It produces DNA and RNA. DNA is a genetic material and RNA takes part in proteins synthesis.