Lipids

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Lipids

  1. 1. Structure & Function of Lipids <ul><li>Lipids are organic compounds found in every type of plant and animal cell. </li></ul><ul><li>They contain the elements CARBON, HYDROGEN and OXYGEN [ but less O 2 than in carbohydrates ] </li></ul><ul><li>All lipids are INSOLUBLE in WATER </li></ul><ul><li>Lipids have many important functions: </li></ul><ul><ul><li>In cell membrane structure - Mechanical Protection </li></ul></ul><ul><ul><li>Hormones - Electrical Insulation of Nerves </li></ul></ul><ul><ul><li>Energy storage molecules - Waterproofing & Buoyancy </li></ul></ul><ul><ul><li>Thermal Insulation </li></ul></ul>
  2. 2. <ul><li>FATS: Solid at room temperature </li></ul><ul><ul><li>SATURATED FATS : all available bonds are occupied by Hydrogen </li></ul></ul><ul><ul><li>Most animal fats are saturated e.g. butter, lard </li></ul></ul><ul><li>OILS: Liquid at room temperature </li></ul><ul><ul><li>UNSATURATED FATS: contain C-C double bonds in the molecule therefore kinks are introduced. </li></ul></ul><ul><ul><li>Oils tend to be more available in plants e.g. sunflower oil, olive oil </li></ul></ul>
  3. 3. Type of Lipids <ul><li>3 types of lipids which are important to cells: </li></ul><ul><li>1. Triglycerides </li></ul><ul><li>Most common type of lipid </li></ul><ul><li>3 fatty acids and a glycerol molecule are linked by an ester bond formed during dehydration synthesis </li></ul><ul><li>2. Phospholipids </li></ul><ul><li>Same as triglycerides except one of the fatty acids molecules is replaced by a phosphate group (PO 4 3 -) </li></ul><ul><li>The phosphate group is polar and so is attracted to water – therefore the phospholipid has two distinct ‘ends’ </li></ul><ul><li>A hydrophilic end (‘water loving’) that dissolves in water and a hydrophobic end (‘water hating’) that is repelled by water </li></ul><ul><li>3. Steroids </li></ul><ul><li>Very different structure – 4 carbon rings with variety of different side chains </li></ul>
  4. 4. Triglycerides cont. <ul><li>The properties of triglycerides are determined by their constituent fatty acids </li></ul><ul><li>DEHYDRATION SYNTHESIS occurs between the hydroxyl group of the glycerol molecule and the carboxyl groups of the fatty acid molecule producing an ester </li></ul><ul><li>Main function = ENERGY STORE e.g. camel hump </li></ul><ul><li>The form in which fatty acids are transported round the body and stored is adipose tissue </li></ul>ANIMATION
  5. 5. Phospholipids <ul><li>Similar to triglycerides but one fatty acid is replaced by a phosphate group which often has other groups attached </li></ul><ul><li>Usually one fatty acid is saturated and one is unsaturated. Most common phospholipid in animal tissue is PHOSPHATIDYLCHOLINE </li></ul><ul><li>The phospholipid has two distinctive ends: </li></ul><ul><li>HYDROPHILIC HEAD that dissolves in water </li></ul><ul><li>HYDROPHOBIC TAIL that repels water </li></ul>This property causes phospholipids to spontaneously form bilayers
  6. 6. Functions of Phospholipids <ul><li>Essential components of cells and organelle membranes </li></ul><ul><li>Components of lung surfactants </li></ul>

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