Difference between plant and animal cells S. No Plant cell Animal Cell Usually they are larger than animal cells Usually smaller than plant cells Cell wall present in addition to plasma membrane and consists of middle lamellae, primary and secondary walls Cell wall absent Plasmodesmata present Plasmodesmata absent Chloroplast present Chloroplast absent Vacuole large and permanent Vacuole small and temporary Tonoplast present around vacuole Tonoplast absent Centrioles absent except motile cells of lower plants Centrioles present Nucleus present along the periphery of the cell Nucleus at the centre of the cell Lysosomes are rare Lysosomes present Storage material is starch grains Storage material is a glycogen granules Figure . : Cell structure and components Functions of cell wall The cell wall plays a vital role in holding several important functions given below . Offers definite shape and rigidity to the cell.
. Serves as barrier for several molecules to enter the cells. . Provides protection to the internal protoplasm against mechanical injury.
. Prevents the bursting of cells by maintaining the osmotic pressure. . Plays a major role by acting as a mechanism of defense for the cells.
. . Cell Membrane The cell membrane is also called cell surface (or) plasma membrane . It is a thin structure which holds the cytoplasmic content called ‘ cytosol ’.
It is extremely thin (less than 10nm). Figure . : Model of Cell membrane b. Secondary wall Secondary wall is laid during maturation of the cell.
It plays a key role in determining the shape of a cell. It is thick, inelastic and is made up of cellulose and lignin. The secondary wall is divided into three sublayers termed as S , S and S where the cellulose microfibrils are compactly arranged with different orientation forming a laminated structure and the cell wall strength is increased. c.
Middle lamellae It is the outermost layer made up of calcium and magnesium pectate, deposited at the time of cytokinesis. It is a thin amorphous layer which cements two adjacent