(a) Centromere it is required for proper chromosome segregation. The centromere consists of two sister constriction chromatids. It is also necessary at the point chromosome attaches to the spindle apparatus during mitosis and meiosos.
(b) Cell wall It gives a definite shape to the cell and protects the cell from mechanical injury and infections. It also helps in cell to cell interaction and act as a barrier for undesirable macromolecules. (c) Smooth ER It helpsin synthesis of lipids, metabolism of carbohydrates, regulation of calcium concentration, drug detoxification and attachment of receptor on cell membrane proteins. The smooth ER also contain enzymes-glucose 6 phosphatase, which converts glucose 6 phosphateto glycogen, essential in glucose metabolism.
(d) Golgi apparatus It is the important site for the formation of glycoprotein and glycolipids. it is also involved ib the synthetic of cell wall materials and also play an important role in formation of cell plate during cell division.
(e) Centrioles They form the base bodyof cilia and flagella and spindlefibres that gives rise to spindle apparatus during cell division animal cells. They help in formation of microtubles and sperm tail. they also help in cell division by forming asters, which acts as spindle pole.
