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  1. 1. AS Biology Core Principles Lipids dr shabeel pn
  2. 2. Aims <ul><li>Elements of lipids </li></ul><ul><li>Structure of glycerol & fatty acids </li></ul><ul><li>Condensation reactions to form triglycerides </li></ul><ul><li>Phospholipids </li></ul>
  3. 3. Introduction to lipids
  4. 4. Introduction to lipids <ul><li>Lipids contain the elements carbon, hydrogen and oxygen. </li></ul><ul><li>They have numerous functions, primarily energy stores in animals and plants. </li></ul><ul><li>Lipids consist of two types of molecules - glycerol & fatty acids. </li></ul>
  5. 5. Glycerol <ul><li>A molecule of glycerol is made up of three carbon atoms. </li></ul><ul><li>Each of these has a hydroxyl group attached to it. </li></ul><ul><li>Hydrogen atoms occupy the remaining positions. </li></ul>
  6. 6. Fatty Acids
  7. 7. Fatty Acids <ul><li>A single fatty acid molecule contains an acid (COOH) group attached to a hydrocarbon chain. </li></ul><ul><li>Hydrocarbon usually denoted by the letter ’R’. </li></ul><ul><li>Saturated = If every carbon atom in the chain is joined by a single C-C bond. </li></ul><ul><li>Unsaturated = at least one C=C bond. </li></ul><ul><li>Polyunsaturated = many double bonds. </li></ul><ul><li>Most animal fats are saturated while most plant fats are unsaturated. </li></ul>
  8. 8. Triglycerides
  9. 9. Triglycerides <ul><li>A triglyceride molecule is made of a glycerol molecule and three fatty acids. </li></ul><ul><li>The molecules join together through the process of condensation losing a molecule of water each time a link is made. </li></ul><ul><li>The link between the glycerol molecule & each fatty acid is an ‘Ester Link’. </li></ul><ul><li>The fatty acids in a lipid molecule can differ in length and can be saturated or unsaturated. </li></ul>
  10. 10. Triglycerides
  11. 11. Phospholipids <ul><li>In phospholipids one of the fatty acids of a triglyceride is substituted by a phosphate group. </li></ul>
  12. 12. Phospholipids
  13. 13. Phospholipids
  14. 14. Lipids & water <ul><li>Triglycerides and phospholipids have hydrophobic and hydrophilic groups. </li></ul><ul><ul><li>What does this mean? </li></ul></ul><ul><ul><li>To what use is this feature put in biology? </li></ul></ul>
  15. 15. More Info <ul><li>To make further notes on Lipids : </li></ul><ul><ul><li>Pages 11 & 12 in Collins </li></ul></ul><ul><ul><li>Pages 69 - 71 Roberts </li></ul></ul><ul><ul><li> </li></ul></ul><ul><ul><li> </li></ul></ul><ul><ul><li> </li></ul></ul>