Nucleus is the largest cellular organelle. It is spherical in shape, with a diameter of about 5 μM. Nucleus is surrounded by a nuclear membrane. The nuclear membrane is porous in nature and the pores are called nuclear pores. The RNA synthesised in the nucleus enters into the cytoplasm through these nuclear pores. Nucleus consists of thick protoplasm (nucleoplasm), which contains various enzymes, free amino acids, lipids, Ca²⁺, Mg²⁺ ions, deoxyribonucleic acid (DNA), and ribonucleic acid (RNA). The main component of nucleus is chromatin, which is present throughout the nucleus and is composed of cellular DNA along with proteins—histones. During cell division, chromatin is divided and is shared equally between the daughter cells. The structure of nucleus is as shown in