Functions
of the main organelles of plant and animal cells. We will be familiar with some
cell organelles, visible under an electron microscope. (a) Cell wall: Cell wall
is the unique and outstanding feature of a plant cell. It is composed of inert
materials. Chemical composition of a wall is much complex. Cellulose,
nitrocellulose, lining, tenpin, submariner are the chemical components of a plant
cell wall. But, bacterial cell wall is composed of protein and lipid. The
primary cell wall is single layered. Secondary cell wall gradually develops
through the compilation of different chemical substances secreted from protoplasm on the middle flagellum. At
the time of development of secondary cell wall, some cavities are formed and
they are celled pits. Cell wall protects a cell from all external injuries. It
gives a cell its rigidity. Cell wall retains the shape and size of a cell. For
exchanging materials with the adjacent cell, plainclothesman are formed in a cell
wall. Cell wall controls the movement of water and minerals. There is no cell
wall around an animal cell. (b) Plasma lemma: The double layered membrane
around the protoplasm of a cell is called cell membrane or plasma lemma. In a
plant cell, cell membrane is attached with the cell wall from the inner side of
the cell. the double layered membrane are called micro villi . It is mainly
composed of lipids and proteins. For its being selectively permeable, the
membrane can control the movement of water and minerals though the process of
osmosis, and separates a cell from its neighboring cells.

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