(a) Centromere is required for proper chromosome segregation. The centromere consists of two sister chromatids. It is also necessary for attachment of chromosomes to the spindle apparatus during mitosis and meiosis.


(b) Cell wall gives a definite shape to the cell and protects the cell from mechanical injury and infections. It also aids in cell to cell interaction and acts as a barrier for undesirable macromolecules.
(c) Smooth ER helps in synthesis of lipids, metabolism of carbohydrates, regulation of calcium concentration, drug detoxification and attachment of receptors on cell membrane proteins.
The smooth ER also contains enzymes-glucose 6 phosphatase, which converts glucose 6 phosphate to glucose essential in glucose metabolism.

(d) Golgi apparatus is an important site for the formation of glycoprotein and glycolipids also involved in the synthesis of cell wall materials and plays an important role in formation of cell plate during cell divisionas well.

(e) Centrioles form the base body of cilla and flagella and spindle fibres that gives rise to spindle apparatus during cell division in animal cells. They help in formation of microtubules and sperm tail. They also help in cell division by forming asters, which acts as spindle pole.