NUCLEUS::
It is the key structure of the living cell like the brain of man in miniature it consists of dense chromosomal network (chromatin) and nucleolus
The whole nucleus is surrounded by a nuclear membrane which is identical to the cell membrane it is perforated by numerous pores and appears to be continuous with endoplasmic reticulum
chromain is the set of heriditary material consisting of deoxyribose nucleic acid (DNA) In the form of genes when the cell divides the chromatin becomes compact and dense and rod like particles called chromosomes becomes distinct each human body cell is made up of 46 chromosomes in addition to DNA nucleus also consists of ribo nucleic acid (RNA)
Nucleolus is a tiny spherical dark staining body consisting of 95% proteins and 5%RNA A nucleus may contain one or more nucleoli the function of nucleolus is synthesis of ribosomal RNA and its packaging with protein to form ribosomes it disappears temporarily during the cell division
most of the body cells contain single nucleus which is round or oval in shape however there are exception e.g skeletal muscle fibres are multinuclear and the floating red blood cells lack the nucleus function of the nucleus are 1.cell division 2.transfer of heriditary characteristics 3.synthesis of protein and enzymes since nucleus contains genetic material that directs functioning of all the parts the nucleus is also considered as the control center of the cell
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