The nucleus is surrounded by the nuclear membrane which consists of two membrane namely outer and inner membrane. the nuclear membrane separates
nucleus  from is also surrounded by ER ( Endoplasmic Reticulum ).
inside the nucleus chromatin material is present which get get condensed when the cell is ready to divide in the chromosomes. Inside the chromosomes genes are present, and inside the genes DNA is present.  
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The structure of nucleus contains nuclear membrane, chromosomes, nucleolus and  cytoplasm. it is a sphere-shaped organelle found in eukaryotic cells. the nucleus contain most of the cells genetic material and is responsible for controlling the cells growth, movement, reproduction and eating.
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