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The Membrane Of The Cell Membrane

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1.0 Introduction
1.1 The Cell Membrane Biological cells have a membrane that separates the contents of the cell from its exterior environment and serves a number of functions. The membrane is partially permeable, facilitating and controlling what materials pass into and out of the cell. The membrane can produce different compartments within the cell in addition to allowing electrical signals to pass along them, playing a role in cell signalling and creating attachment sites for enzymes and molecules involved in the metabolism (Keeton, 1983, p. 71).
1.2 The Phospholipid Bilayer
The membrane of the cell is composed of a Phospholipid Bilayer with various protein molecules floating within it phospholipids are fats and are constructed of two fatty acid tails that are hydrophobic and a Phosphate head that is hydrophilic. The heads orientate themselves towards the water molecules outside of the cell with the hydrophobic tails pointing away from the water molecules. A second tier of phospholipids forms a mirror image with the heads pointing towards the water molecules inside the cell itself. These two tiers of Phospholipids form the Phospholipid Bilayer (Keeton, 1983, p. 71). Figure 1 Phospholipid Bilayer
1.3 The Fluid Mosaic Model
The Fluid Mosaic Model (Keeton, 1983, p. 71) shows that within the Phospholipid Bilayer are a number of proteins that float freely and form a ‘mosaic’ pattern. These proteins can be intrinsic and exist through the complete thickness of the membrane

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