The Membrane And The Cell Membrane Essay

1131 Words Aug 14th, 2015 null Page
The plasma membrane also known as the cell membrane is found in every cell. The cell membrane is around 7-10nm, making it difficult to view even with a transmission scanning electron microscope (it only shows a double black line), this means that no one knows exactly what the membrane looks like. All membranes have the same basic structure made up from phospholipids (fats). The membrane is made up of a phospholipid bilayer; consisting of a polar phosphate head and two fatty acid tails. The head is made from an alcohol and glycerol group and has a non-polar fatty acid tail made up from two strings of hydrogen and carbon atoms. The head cannot pass through the tails giving the bilayer stability. Despite the stability of the bilayer, the phospholipid molecules are not bonded together. The head is also hydrophilic (attracted to water molecules), because it has an unevenly distributed charge that is attracted to the charges in the water. Whereas the tails are hydrophobic with evenly distributed charges that repel in the water. The charges of the water explain the structure of the membrane; as the fatty acids repel water so the tail end of the molecule has to face inwards away from the water. Thus, so the phosphate head has to go on the outside as it is 'water loving '. In 1972, Singer and Nicolson proposed their theory on the structure of the plasma membrane. This theory is known as the fluid mosaic model, which is now widely recognised and accepted as the membrane structure.…

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