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Lipids

Lipids. Lipos (Greek) - fat. Lipids. Lipids are isolated from cells and tissues by extraction with non-polar solvents. These compounds include:. neutral fats and oils (CHO) phospholipids (CHOP) waxes aliphatic alcohols steroids terpenes.

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Lipids

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  1. Lipids Lipos (Greek) - fat

  2. Lipids Lipids are isolated from cells and tissues by extraction with non-polar solvents. These compounds include: neutral fats and oils (CHO) phospholipids (CHOP) waxes aliphatic alcohols steroids terpenes There are essentially two types of lipids: esters and non-esters.

  3. The principal forms of nutrition • fats and oils • carbohydrates • proteins Within our bodies, the total amount of glycogen, a carbohydrate stored in the liver, only contains a reserve of energy for some fifteen hours. On the other hand, one can store sufficient energy in the form of fats to last for months! So let’s look at them!

  4. Neutral fats and oils An ester - a triacylglycerol! (a.k.a. triglycerides)

  5. Hydrolysis of these esters Most naturally occurring fatty acids have an even number of atoms of carbon.

  6. Common fatty acids myristic acid CH3(CH2)12CO2H CH3(CH2)14CO2H palmitic acid stearic acid CH3(CH2)16CO2H oleic acid CH3(CH2)7CH=CH(CH2)7CO2H CH3(CH2)4CH=CHCH2CH=CH(CH2)7CO2H linoleic acid CH3(CH2)2CH=CHCH2CH=CHCH2CH=CH (CH2)7CO2H linolenic acid

  7. Melting points Stearic acid 70C (C18) Palmitic acid 63C (C16) Myristic acid 54C (C14) Oleic acid 16C (C18) 1 x C=C Linoleic acid -5C (C18) 2 x C=C Linolenic acid -11C (C18) 3 x C=C

  8. Olive oil oleic acid, 83% palmitic acid, 6% linoleic acid, 7%

  9. Soaps - saponification

  10. How do soaps work? hydrocarbon chain carboxyl group

  11. Micelles Soaps exist as micelles which are spherical clusters with the polar groups at the surface and the nonpolar chain in the interior. grease

  12. Detergents Soaps have a major undesirable property - they form insoluble salts in “hard water” - that is water containing Ca2+, Mg2+ or Fe3+ ions. Synthetic detergents form soluble salts with these ions. These detergents are salts of sulfonic acids or alkyl hydrogen sulfates.

  13. Detergents glycerol

  14. sodium dodecylbenzenesulfonate

  15. Hardening of oils The conversion of vegetable oils into solids by hydrogenation of some or all of the carbon - carbon double bonds in the fatty acid residue.

  16. Phospholipids There are two types of phospholipids: phosphoglycerides and sphingolipids. Here are the two “backbones”:-

  17. Phosphoglycerides Phosphoglycerides contain an amino-alcohol, whose OH is forms an ester linkage to the phosphate group. The two other glycerol OH groups form esters links to fatty acids. In phosphatidylcholine, R is saturated and R’ is unsaturated e.g. R = carbon chain of palmitic acid and R’ = carbon chain of oleic acid. (R) The phosphate group is also bonded to an amino alcohol…choline in lecithins.

  18. Cephalins • isolated from the brain or spinal cord • the nitrogen base is 2-aminoethanol or serine

  19. Phospholipids • phosphatides are the most polar lipids • very soluble in both non-polar solvents and water • seem to serve as structural bridges between water-soluble proteins and non-polar lipids • play roles in the process of secretion, ion transport and cell membrane permeability

  20. Waxes n = 24 and 26; m = 28 and 30 (from beeswax)

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