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Lipids

Lipids. Lipids contain the elements Carbon Hydrogen Oxygen There are two main groups: Triglycerides Phospholipids. fatty acid. glycerol. Triglycerides. one glycerol molecule 3 fatty acids. H. H. C. OH. H. C. OH. H. C. OH. H. Glycerol C 3 H 8 O 3. Fatty Acids.

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Lipids

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  1. Lipids

  2. Lipids contain the elements Carbon Hydrogen Oxygen There are two main groups: Triglycerides Phospholipids

  3. fatty acid glycerol Triglycerides one glycerol molecule 3 fatty acids

  4. H H C OH H C OH H C OH H Glycerol C3H8O3

  5. Fatty Acids carboxylic acid group (COOH) joined to a long tail of carbon and hydrogen atoms The length of the hydrocarbon tail varies, giving rise to the various fatty acids. The tail is normally written as R, giving the formula R.COOH

  6. Fatty acids • Organic acids with a carboxyl (-COOH) group at the end • Joined to the carboxyl group is a long hydrocarbon tail • This tail differs in each fatty acid • The properties of a lipid depend on the fatty acids they contain • Fatty acids vary in 2 ways – • the length of the HC chain • how saturated the molecule is.

  7. H H H H H O H C C C C C C OH H H H H H Fatty Acid R.COOH R COOH

  8. Saturated Fatty Acids • All bonds between carbon atoms are single • high melting points • solids at room temperature • associated with animal fats

  9. Unsaturated Fatty Acids • One or more doublebonds between carbon atoms • low melting points • liquid at room temperature • associated with plant oils

  10. Formation of a triglyceride • Formed as a result of 3 condensation reactions between glycerol and 3 fatty acids • involving the –OH group of glycerol and the –COOH group of the fatty acid • These reactions result in the formation of 3 molecules of water. • The bond between glycerol and the fatty acid is called an ester bond.

  11. Formation of a triglyceride H H OH OH O O OH H H C C H H OH OH O O C C OH H H OH OH O O C C OH H H condensation HOOC.R OC.R R.COOH H2O ester bond HOOC.R OC.R R.COOH H2O HOOC.R OC.R R.COOH H2O fatty acids glycerol triglyceride 3 water

  12. Phospholipids Composed of glycerol, 2 fatty acids and a phosphate group. Draw and label diagram p17

  13. Hydrophilic (water loving) head contains glycerol and phosphate group Hydrophobic (water hating) tail contains 2 fatty acids

  14. The glycerol and phosphate part is polar and dissolves in water (hydrophilic) • The fatty acids are non-polar and insoluble (hydrophobic) • If placed in water the phosphate heads dip into the water and the tails stick out, forming a monolayer • Draw diagram page 17

  15. Hydrophobic tails AIR Hydrophilic heads WATER

  16. When shaken in water phospholipids form hollow balls called micelles; the hydrophilic head on the outside and the hydrophobic tails pointing inside.

  17. Hydrophilic heads Phospholipid bilayer Hydrophobic tails Hydrophilic heads Phospholipids are important in cell membranes where they form a phospholipid bilayer; a double layer, heads out, tails in.

  18. Functions of lipids • Cell membrane • Energy store • Insulation • Waterproofing/repellent/wax covering on plant cuticle/exoskeletons • Buoyancy • Protection • Storage of fat soluble vitamins

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