Write the functions of the following
(a) Centromere (b) Cell wall
(c) Smooth ER ( d) Golgi apparatus
( e) Centrioles

Explanation

(a) Centromere. It is a lightly-stained constriction on a chromosome at which two sister chromatids are joined to each other. It has two disc-like kinetochores on which chromosomal spindle fibres are attached during cell division.
(b) Cell wall: (i) It Protects the cell from mechanical injuries and entry of germs. (ii) It provide mechanical support and definite shape to cell. (iii) Suberin and cutin prevent evaporation of water. (iv) It helps in cellular interactions and also act as barrier to undesirable biomolecules.
(c) SER. It is involved in synthesis of lipids (e.g. triglycerides) and steroid hormones (e.g. testosterone, Estrogens, etc.), contraction of muscle cells and detoxification of harmful drugs and carcinogens.
(d) Golgi apparatus. It packages the cellular secretions into the secretory vesicles, glycosylation (addition of carbohydrates) of proteins and lipids, formation of acrosome, Primary lysosomes and cell plate.
(e) Centrioles. These form asters and spindle apparatus during cell division in animal cells, and form basal bodies to give rise to cilia and flagella.