Cell membrane function and difference-digieduco

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  Functions of cell membrane : (a) The proteins and enzymes present in the cell membrane helps in the transport of certain substances like sugar, sodium and other ions etc. across the cell membrane. (b) Cell membrane protects the internal structures of the cell and different organelles of the cytoplasm. (c) It maintains the shape of the cell. (d) It acts as a selective permeable membrane because it allows to pass certain substances while others are not, hence it helps in the transport of selective materials from and to the cells. (e) The membranes on the cytoplasmic organelles and nucleus most probably formed from the plasma membrane. (f) Other important functions of cell membrane of the cells are endocytosis and exocytosis . Endocytosis is the process by which materials are transported into the cells by the formation of vesicles. It includes two processes-phagocytosis (cell eating) and pinocytosis (cell drinking). The reverse process of endocytosis is exocytosis. During th...
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Movements of protoplasm-digieduco

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Protoplasm exhibits movements within the cell. Such movements are called streaming movements of protoplasm. The streaming movements of the protoplasm are also commonly called cyclosis. There are two types of streaming movements, such as :
Movements of protoplasm-digieduco

1. Rotation-In this case the movement of protoplasm is regular and in definite
direction along the cell wall. It may be clockwise or anti-clockwise in direction. e.g, Vanisneria, Elodea (Hydgocharitaceae) etc.

2. Circulation-In circulation, the movement of protoplasm is not regular ;in this
type, the course of protoplasmic movement is irregular, i.e. in several directions, e.g. staminal hairs of Rhoeo discolor (Commelinaceae).

Besides the above two types of movements, protoplasmic movements are also exhibited by naked protoplast of some cells.

(a) Amoeboid-Like unicellular animal Amoeba, slime moulds (Myxomycetes) exhibit a type of movement due to rhythmic contraction and relaxation of the protoplasm known as amoeboid movement.

(b) Ciliary-Naked protoplast moves from one place to another due to the presence of one or more whip-like protoplasmic processes, called cilia, e.g. reproductive cells like zoospores, spermatozoids etc.

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