Macro mols lipids lesson


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Macro mols lipids lesson

  1. 1. LipidsFunction5 classes / types
  2. 2. Lipid Function1. Long-term energy storage (fat)2. Form cell membrane (phospholipids)3. Messaging (hormones)4. Insulation5. Cushioning of Internal Organs
  3. 3. Lipid FunctionWhy are lipids well suited for long term energy storage? Contain many high energy bonds between carbon and hydrogen Contain twice as much energy per gram than carbohydrates (very concentrated) Thus a much more compact form of storage than carbohydrate Animals store fats in adipose cells
  4. 4. Types of Lipid1. Fat: Triglyceride / triacylglycerol2. Phospholipid3. Steroid4. Wax5. Carotenoid
  5. 5. 1. Fat Structure Fatty acid also known as Glycerol Fatty acid triglyceride or Fatty acid triacylglycerol Consists of:  1 glycerol backbone  3 fatty acid chains
  6. 6. Glycerol Structure Fatty acid Basic structure: Glycerol Fatty acid  3 carbon molecule Fatty acid  each carbon has a hydroxyl group attached the alcohols are sites for condensation reactions
  7. 7. Fatty acid structure Basic structure:  Unbranched chain of carbons  A carboxyl group at one end Fatty acid chains can differ from each other in two ways:  Length of carbon chain: 4-24  Saturation (number of double bonds) - Saturated - Monounsaturated - polyunsaturated
  8. 8. Essential Fatty AcidsThe most common fatty acid in living organisms is palmitic acid.Humans can synthesize and use palmitic acid:CH3(CH2)14CO2Hor
  9. 9. Essential Fatty AcidsEssential fatty acids are those that humans can notsynthesis and must ingest.Humans can not create double bonds in fatty acidsbeyond C10.1) alpha-Linolenic Acid (an omega-3 fatty acid)
  10. 10. Essential Fatty Acids2) Linoleic Acid (an omega-6 fatty acid)
  11. 11. Properties of Fatty acids Type Saturated Unsaturated Structure Single bonds Double bonds, kinkState at r.t. Solid liquid Origin Animals PlantsExamples Butter, lard Olive oil, essential FA (omega-3/6 fish oil)
  12. 12. Property of Saturated Fats  Saturated fats are solid!  Butter sculpture at the CNE 2012  Can you guess who this is?
  13. 13. Forming a triacylglycerol Condensation reaction between:  Hydroxyl on glycerol  Carboxyl on fatty acid Results in an ester bond
  14. 14. Triacylglycerol model
  15. 15. 2. Phospholipid structure Phosphate / Polar  Glycerol backbone Glycerol group Fatty acid  2 fatty acids chains Fatty acid  phosphate/polar group
  16. 16. 2. Phospholipid structure Polar head: negatively charged, hydrophilic tail Nonpolar tails: fatty acids, hydrophobic Amphipathic: exhibiting both hydrophilic and hydrophobic properties
  17. 17. Polar Head Groups
  18. 18. Polar Head Groups
  19. 19. Self-assembly of phospholipid Condition: in water (aqueous) Self-assembly = spontaneous aggregate Due to hydrophobic interactions Micelle: single layer of phospholipid with polar head facing out, nonpolar tails facing inward
  20. 20. Self-assembly of phospholipid Phospholipid bilayer have a double layer of phospholipids where the nonpolar tails aggregate forming a hydrophobic core This is the basic structure of the plasma membrane
  21. 21. Plasma Membrane Membranes are made of a bilayer of phospholipids.
  22. 22. Plasma Membrane
  23. 23. Phospholipid Bilayer
  24. 24. 3. Steroid Carbon skeleton, 4 interconnected rings Three 6C rings, one 5C ring Common examples:  cholesterol  hormones – estrogen, testosterone
  25. 25. SteroidCholesterol TestosteroneCortisone Aldoesterone
  26. 26. 4. Wax StructureLong chain hydrocarbons Primarily wax esters: a long chain hydrocarbon with an ester group that is not a triglyceride Could also involve alcohol, aldehyde & ketone groups
  27. 27. Properties of Wax Solid at room temperature Becomes liquid when melted has plastic properties: deforms under pressure without application of heat thermoplastic is a polymer that turns to a liquid when heated and freezes to a very glassy state when cooled sufficiently
  28. 28. Natural WaxNatural Animal wax: beeswax, lanolin, shellac Vegetable waxes: soy, jojoba, carnauba Mineral waxes: petroleum (paraffin) from fossil fuelsSynthetic Polypropylene, Polyethylene
  29. 29. 5. Carotenoids Natural fat-soluble pigment Backbone: 40 carbon molecules with a polyene chain with alternating single and double bonds terminated by cyclic end-groups
  30. 30. Polyene structure
  31. 31. Carotenoid: Plant Pigment Found in plants, algae, photosynthetic bacteria Pigment needed for photosynthesis in addition to chlorophyll e.g. beta-carotene in carrot
  32. 32. Carotenoid: use in animals Detecting light: e.g. retinal absorbs light in retina Serves as antioxidant: double bonds absorb excess energy from other molecules, protecting cells and tissues from damaging effects of free radicals Source for vitamin A
  33. 33. What is common to all lipids? The 5 forms of lipids studied are not built upon any common monomer. What unified these lipids so that they are all classified under the ‘lipid’ category? In other words, what makes a lipid, a lipid?
  34. 34. HW Question Why is glycerol not classified as a triose (3C monosaccharide)? Explain how saturation in a fatty acid chain affects fluidity. Explain how the length of the fatty acid chain affects fluidity.