What Are The Various Parts Of A Nucleus Of A Cell?

The nucleus consists of a small spherical mass of denser protoplasm (a jelly like substance), the nucleoplasm, surrounded by a membrane called nuclear envelope. It is found in the cytoplasm of the cell and controls the normal cell activities. Within the nucleus are the following.
A) A network of long thread-like structures called chromatin. The chromatin threads contain hereditary materials. These materials control the activities of the cell. During cell division the chromatin threads condense and become highly coiled structures called chromosomes. Under the microscope the chromosomes appear as thick rod-shaped structures.
Chemical analysis shows that each chromatin thread is made up of proteins and a compound called deoxyribonucleic acid or DNA. It is in the DNA that hereditary information is stored.
B)Spherical structures called nucleoli. Each nucleolus plays a part in the building up of proteins.
C)A nuclear envelope which separates the nucleus from the surrounding cytoplasm.

The nucleus is responsible for the cell reproduction. It is needed for the continuing life of the cell, as well as for the repair of worn-out cells. Cells without a nucleus, for example, the red blood cells of a mammal have a short life span and are unable to reproduce.