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CHAPTER 13 LIPIDS

CHAPTER 13 LIPIDS. LIPID. fatty acids. waxes. steroids. triglycerides. Lipids. A heterogeneous class of naturally occurring organic compounds classified together on the basis of common solubility properties. insoluble in water, but soluble in organic solvents . FATTY ACIDS.

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CHAPTER 13 LIPIDS

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  1. CHAPTER 13 LIPIDS

  2. LIPID fatty acids waxes steroids triglycerides Lipids • A heterogeneous class of naturally occurring organic compounds classified together on the basis of common solubility properties. • insoluble in water, but soluble in organic solvents • .

  3. FATTY ACIDS • Carboxylic Acid with long hydrocarbon tail

  4. FATTY ACIDS • Usually straight chains (no branching) • Sizes usually range from C10 to C20 • Usually have an even number of carbons • Can be saturated (no C=C bonds) or unsaturated (has C=C bonds)

  5. Monounsaturated – one C=C Polyunsaturated- more than one C=C

  6. Molecular Shapes C=C causes “kinking” of the carbon chain

  7. SATURATED • Can pack closely together • High Melting point • Solid • Animal fat • UNSATURATED • Kinks prevent close contact • Lower Melting point • Liquid • Plant and fish oil

  8. WAXES • Ester formed from a long chain carboxylic acid (fatty acid) and a long chain alcohol

  9. BEESWAX-Glands under the abdomen of bees secrete a wax, which they use to construct the honeycomb. The wax is recovered as a by-product when the honey is harvested and refined. LANOLIN - The grease obtained from the wool of sheep during the cleaning or refining process is rich in wax BIRD WAXES -Special glands of birds secrete waxes that consist largely of wax esters. The main purpose of the waxes is to give a water-proof layer to the feathers. MARINE WAXES - Waxes appear to have a variety of functions in fish, from serving as an energy source to insulation and buoyancy. PLANT WAXES -The wax provides protection from disease and insects, and helps the plants resist drought.

  10. TRIGLYCERIDES

  11. FATS AND OILS • Fats and oils are triglycerides which are triesters of glycerol. • Fats Usually from animal sources. Are solids at room temperature. Contain a high degree of saturated fatty acids. • Oils Usually from plant and fish sources. Are liquids at room temperature. Contain more unsaturated fatty acids.

  12. HYDROGENATION

  13. PARTIAL HYDROGENATION →

  14. TRANS ISOMER CIS ISOMER

  15. TRANS FATTY ACIDS

  16. Raises level of bad cholesterol (LDL) • Decreases level of good cholesterol (HDL) • Arteries become clogged • Increase in strokes • and heart attacks

  17. REACTIONS OF TRIGYLCERIDES HYDROLYSIS

  18. SAPONIFICATION • Hydrolysis using a base to give glycerol and 3 • fatty acid salts (soap)

  19. Fig. 18-2, p. 460

  20. Fig. 18-3, p. 460

  21. EMULSIFYING AGENTS • Oil and vinegar salad dressing • Mayonnaise Hollandaise sauce • Chocolate Soap/detergent • Lotions Creams

  22. SUMMARY

  23. Complex Lipids

  24. Fluid Mosaic Model

  25. STEROIDS A broad class of compounds that have the same structural feature:

  26. Most abundant steroid in the human body. Essential component of cell membranes. Precursor of other important steroids. CHOLESTEROL • Synthesized by liver and present in foods. • Strong correlation between cholesterol blood levels and atherosclerosis.

  27. LIPOPROTEINS

  28. HIGH DENSITY LIPOPROTEINS (HDL) More protein; less cholesterol Transports cholesterol from cells back to the liver LOW DENSITY LIPOPROTEINS (LDL) Less protein, more cholesterol Transports cholesterol from the liver to cells

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