We will be familiar with some cell organelles,visible under an electron microscope..
Cell wall is the unique and outstanding feature of a plant cell.It is
composed of inert materials.Chemical composition of a cell wall is much complex.Cellulose,hemicelluloses,lignin,pectin,suberin 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 lamellum.At the time of development of secondary cell wall, some cavities are formed and they are called 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,plasmodesmata are formed in a cell wall.
Cell wall controls the movement of water and minerals.There is no cell wall around an animal cell....
Plasma lemma..
The double layered membrane around the protoplasm of a cell is called cell membrane or plasmalemma.In a plant cell,cell membrane is attached with the cell wall from the inner side of the cell.The double layered membrane is much flexible.The foldings of a cell membrane are called microvilli.It is mainly composed of lipids and proteins.For its being selectively permeable,the membrane can control the movement of water and minerals through the process of osmosis,and separates a cell form its neighbouring cells....
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