The three main components of biological membranes are carbohydrates, proteins and lipids, and each of them has an important role to play in the functioning of membranes.
The first part of this document will detail the various compounds of the membranes and study their role in its operation. We will discuss the fluidity that is essential for its effective functioning and the factors it depends on. Subsequently we will discuss the molecular organization and structure of biological membranes and see how they can be placed in the monolayer, bi-layer or micelle form. To conclude, the main functions of the membrane will be described.
[...] Conclusion The main components of the membrane proteins are carbohydrates and lipids. These are used in varying amounts depending on the function of the membrane, and are important for the functioning of the cell The flow is necessary for the functioning of the membrane and depends on the bicouche or saturation of fatty acids. Biological membranes such as the bi-layer lipid-mosaic fluid model of Singer and Nicholson (1972) The two main functions of membranes: Compartmentalization (Separation of internal-external environments) Transportation of molecules [...]
[...] These layers are classified into two categories: Multi lamellar: These are characterized by several concentric membranes bounding a cavity of a small diameter. Uni lamellar: The size of these layers varies between 20 nm and 1 micron. These lipid bi-layers tend to form stable discoidal micelles (without water inside). d. Structuration trilaminar In cross section, the electron microscope images reveal a typical structure called tri laminar because it has two dark layers ( 2.5 nm) enclosing a leaflet of clear lipid-protein sandwich. [...]
[...] The phospholipids and phosphoglycerides These are most abundant in membranes and are derived from glycerol. They are composed of fatty acids, glycerol, phosphoric acid and one molecule of a specific phospholipid (bequeathed to an alcohol group by phosphoric acid ester: Serine, Choline, Ethanolamine and Inositol). At a physiological pH value, the negatively charged phospholipids are phosphatidyl, serine and nositol. Grouping: Serine, Choline, Ethanolamine and Inositol are hydrophilic, and therefore, when they are attached to a negatively charged phosphate they form a highly water soluble compound. [...]
[...] Molecular organization of biological membranes, or the structure of biological membranes Through a mixture of phospholipids (lipid dominant in the membrane) and water, structures that spontaneously assemble are obtained, in order to exchange maximum hydrophobic interactions. a. Monolayers: (not found in organisms) A theoretical approach A monolayer is formed at the air / water contact when the phospholipids combine with water. This film takes up maximum available space and consists of molecules oriented in the same manner. The hydrophobic group plunges into the water and protrudes above the surface (to air) b. [...]
[...] Many fundamental cellular processes such as the movement of cells, their growth, division, secretion and endocytosis, would not have been possible if the membranes were rigid and without fluidity. Fluidity is therefore essential, so that the cells are able to respond to changing conditions by changing the types of phospholipids that make up the membranes Fluidity due to lipids The fluidity of the bi-layer depends on its nature. The transition from orderliness to disorder takes place at a temperature between 10 to 40 degrees, at which the structure of the bilayer changes. [...]
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