Cell Membrane Structure

CELL MEMBRANE STRUCTURE The cell membrane is the boundary between living cells and their surroundings which are non-living parts. With a thickness of 8 nm, the cell membrane regulates the in and out traffic of substances needed by the cell from outside to inside the cell and vice versa. The main composition of cell membranes is lipids, proteins, and a small amount of carbohydrates. The types of lipids that make up biomembranes are phosphoglycerides, sphingolipids and steroids. The presence of lipids in cell membranes makes them have amphipathic properties, with hydrophilic head areas and hydrophobic tail areas. Cell membranes have lipids, proteins and carbohydrates that can move randomly within the plane of the membrane but rarely change places transversely across the membrane. The nature of the membrane is fluid to maximize its function in conditions of falling or rising environmental temperatures. If the membrane freezes, its permeability will change because it is possible that the enzymatic proteins will become inactive. The presence of lipids in cell membranes can be adjusted to environmental conditions as a form of adaptation resulting in changes in their composition. Membranes are intermolecular bonds with hydrophobic interactions, which are much weaker than covalent bonds, so they are not static sheets of molecules and are strongly bound between molecules. Biomembranes with dominant phospholipids provide boundaries for cells and cells and also between organelles within the cell as well as limiting the presence of viruses on the outer surface. Unlike proteins, amino acids and polysaccharides, cell membranes are composed of non-covalent bonds in their composition. The main components that make up biomembranes are phospholipids, giving them a sheet-like shape. The type of structure of a biomembrane in the form of phospholipids or a mixture of many types of phospholipids depends on many factors, including the length of the fatty acid chain, the level of saturation, and temperature. Of the three possible structures, the hydrophobic effect is caused by the fatty acid chains becoming aggregated and preventing water from leaving the 'inside' circle (liposome). Meanwhile, the micelle structure is a natural form of phosphoglyceride, where the fatty acid chains generally form clumps when placed in liquid conditions because of their hydrophobic nature. Under appropriate conditions, phospholipids will produce a composition in cells that spontaneously forms a symmetrical phospholipid bilayer layer. Each phospholipid layer in this lamella structure is called a sheet. The fatty acid chains of each sheet minimize contact with water by stacking tightly together and together forming the center of the bilayer, resulting in a tight gap between the sheets with a distance of 3nm. The composition of the phospholipid bilayer is a nonpolar tail which is stable and has a hydrophobic impact due to the presence of van der Waals bonds between them. Ionic and hydrogen bonds also stabilize the phospholipid heads with each other, thus providing a hydrophilic condition. Phospholipid bilayers can range in size from micrometers (μm) to millimeters (mm) in length or width and contain ten to billions of phospholipid molecules. Due to its primarily hydrophobic nature, the bilayer is usually impermeable to salts, sugars, and many small hydrophilic molecules. The phospholipid bilayer is the basic structure of all biomembranes, although sometimes other molecules are also present (cholesterol, glycolipids, proteins), so biomembranes with their main hydrophobic properties provide two boundaries for waterdominant environmental conditions and a permeable boundary. Cell membranes have proteins that are integrated in the lipid bilayer, the existence of which really depends on the type, location and activity of the cell in question. Proteins can be on the outside, inside or even embedded in the lipid bilayer. The two main populations of membrane proteins are integral proteins, generally transmembrane proteins, with hydrophobic regions that extend entirely along the hydrophobic interior of the membrane. The second protein is a peripheral protein that is not embedded in the phospholipid bilayer at all, and is loosely bound to the membrane surface.