The Fundamental unit (Basic Unit) of life is the cell.
Type Of Cells:-
1). Eukaryotic Cell (Nucleus is present found in animals and plants.
2). prokaryotic Cell (Nucleus is absent found in the bacteria.
Structure of Cell-Cell Diameter 10-20 μm.
Based on three Principal
1). Cell Membrane
2). Nucleus and its Chromosomes
3). Cytoplasm and its Organelles
Diagram:-
1). Cell Membrane:- Structure(Fluid Mosaic Model):- Cell Membrane consists of a double layer of molecules in which protein is embedded.
A). The lipids normally 20-40% of the dry weight of cell Membrane
B). The protein 60-70% of the dry weight of cell Membrane and are of two types.
1). Lipoproteins:-(Protein Containing Lipids):-Functions as enzymes and ion, channels.
2). Glycoproteins:- (Protein Containing Carbohydrates):- Functions as receptor for hormones and neurotransmitters.
A). Some Proteins are located in the inner surface of the Membrane (Intrinsic proteins).
B). Some Proteins are located in the other surface of the Membrane (Extrinsic or Peripheral proteins)
C). While some extent through the Membrane (TransMembrane proteins).
D). Clear area formed by Biomolecular thickness of lipid Molecules (phospholipids, cholesterol, and glycolipids)
Functions Of Cell Membrane
1). Protective
2). Digestive
3). Property of selective permeability.
4). Insulating properties(Rubber have High Insulating properties)
5). It provides a framework for the arrangement of an ordered sequence of proteins molecules (Enzymes pumps, Receptions, Ions, Channels, Carriers
6). It links adjacent cells together by junctional complex to form tissues.
Functions
1). Intrinsic proteins serve mainly as enzymes.
2). Extrinsic proteins contribute to be cytoskeleton(Framework of cells).
3). Transmembrane proteins serve as:
A). Channels:- Through which ions or small water-soluble substances can diffuse
B). Carriers:- Which passively or actively transport material across lipid layers.
C). Pumps:- Which actively transport material across lipid layers.
D). Receptors:- Which activated initial intercellular reaction.
The number of receptors in a cell is not constant they can be increased or decreased in response to various stimuli and their property change with change in physiological condition
Example:- When hormones or neurotransmitters are present in excess the number of active receptors decreases when the deficiency number of receptors increases.
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