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Macro mols   lipids lesson
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Macro mols lipids lesson


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  • 1. LipidsFunction5 classes / types
  • 2. Lipid Function1. Long-term energy storage (fat)2. Form cell membrane (phospholipids)3. Messaging (hormones)4. Insulation5. Cushioning of Internal Organs
  • 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. Types of Lipid1. Fat: Triglyceride / triacylglycerol2. Phospholipid3. Steroid4. Wax5. Carotenoid
  • 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. 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. 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. Essential Fatty AcidsThe most common fatty acid in living organisms is palmitic acid.Humans can synthesize and use palmitic acid:CH3(CH2)14CO2Hor
  • 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. Essential Fatty Acids2) Linoleic Acid (an omega-6 fatty acid)
  • 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. Property of Saturated Fats  Saturated fats are solid!  Butter sculpture at the CNE 2012  Can you guess who this is?
  • 13. Forming a triacylglycerol Condensation reaction between:  Hydroxyl on glycerol  Carboxyl on fatty acid Results in an ester bond
  • 14. Triacylglycerol model
  • 15. 2. Phospholipid structure Phosphate / Polar  Glycerol backbone Glycerol group Fatty acid  2 fatty acids chains Fatty acid  phosphate/polar group
  • 16. 2. Phospholipid structure Polar head: negatively charged, hydrophilic tail Nonpolar tails: fatty acids, hydrophobic Amphipathic: exhibiting both hydrophilic and hydrophobic properties
  • 17. Polar Head Groups
  • 18. Polar Head Groups
  • 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. 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. Plasma Membrane Membranes are made of a bilayer of phospholipids.
  • 22. Plasma Membrane
  • 23. Phospholipid Bilayer
  • 24. 3. Steroid Carbon skeleton, 4 interconnected rings Three 6C rings, one 5C ring Common examples:  cholesterol  hormones – estrogen, testosterone
  • 25. SteroidCholesterol TestosteroneCortisone Aldoesterone
  • 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. 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. Natural WaxNatural Animal wax: beeswax, lanolin, shellac Vegetable waxes: soy, jojoba, carnauba Mineral waxes: petroleum (paraffin) from fossil fuelsSynthetic Polypropylene, Polyethylene
  • 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. Polyene structure
  • 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. 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. 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. 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.