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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Cytoplasm-digieduco

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Cytoplasm comprises the living, hyaline, jelly-like and viscous transparent semi-fluid portion of the protoplast. It forms a granular ground substance in which nucleus, plastids and other cell inclusions, both living and non-living, are embedded.

Cell plasm i.e. cytoplasm is the substance which fills up the space between the nucleus and the cell wall. Sometimes. the cytoplasmic portion of the protoplast is called cytosome which literally means the ‘cell body’. Cytoplasm is a very complex structure both from physical and chemical point of view. It contains various organic and inorganic substances; those substances may occur in various states such as colloidal condition, true solutions and crystals.
Cytoplasm-digieduco

The hyaline ground substance of the cytoplasm is called hyaloplasm. The non-granular outermost membrane-like layer of cytoplasm is called ectoplasm, plasma membrane or plasmalemma. The plasma membranes are characterised by their selective permeability to the passage of different substances through them. The granular general mass of cytoplasm is known as endoplasm. The layer of cytoplasm surrounding or bounding the vacuole is termed tonoplasm or vacuolar membrane.

On the basis of the difference in viscosity, the cytoplasm is often differentiated into two regions, e.g. (l) plasmagel-it is the much more viscous portion of the cytosome forming a cortical layer of variable thickness just beneath the plasma membrane or ectoplasm and (2) plasmasol-it is the more fluid portion lying further inside.

The cavities or vacuoles formed within the cytoplasm are filled up with liquid, called the cell-sap. The cell-sap is watery and non-protoplasmic liquid containing various substances either in solution or in colloidal condition or in crystals viz. inorganic salts. carbohydrates, proteins, colouring matters etc.

In a young cell, cytoplasm completely fills up the space . As the cell grows, the growth of the cytoplasm does not compete with the growth of the cell wall. thereby small cavities are formed within the cytoplasm-these are called vacuoles. Finally in adult condition, all the vacuoles fuse with one another forming a big vacuole in the centre of the cell. Thereby the cytoplasm together with all inclusions is pushed towards the inner surface of the cell wall forming a thin lining layer-this thin lining layer of cytoplasm is called primordial utricle.. 

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