LIPIDSS

• Lipids

  • insoluble in water, soluble in nonpolar organic solvents
• Fatty acids: Naturally occuring monocarboxylic acid, has even number C atoms and chain that is unbranched
• Unsaturated fatty acid - one or more double bonds
• Omega-3 fatty acids have three double bonds starting from the third carbon atom from the end of the chain
• Omega-6 fatty acids have six double bonds starting from the sixth carbon atom from the end of the chain
• Essential fatty acids cannot be synthesized by humans and must be obtained through diet
• Linoleic acid is an essential omega-6 fatty acid found in vegetable oils, nuts, seeds, and meat.
• LIPIDS


  Not soluble in water but soluble in nonpolar organic solventssolvents
• Lipids


  • Do not have a common structural feature
  • Naturally occurring monocarboxylic acids with an even number of carbon atoms in an unbranched chain (saturated, monounsaturated, polyunsaturated)
• Saturated fatty acids


  No double bonds eg ( palmitic acid )
• Monounsaturated fatty acids


  One C=C double bond present eg. (oleic acid)
• Polyunsaturated fatty acids


  Two or more double bonds present eh. (linoleic acid)
• Types of unsaturated fatty acids


  • Omega-3 (3 carbons away from methyl end)
  • Omega-6 (6 carbons away from methyl end)
• Water solubility of fatty acids


  Function of Carbon chain length. Decreases as chain length increases
• Melting point of fatty acids


  Influence by both chain length and degree of unsaturation ( C chain increase; Melting point increases)
• Triacylglycerols


  Storage material, formed from esterification of glycerol with 3 identical or different fatty acids
• Saturated fats

  Solid at room temperature
• Unsaturated fats


  Liquid at room temperature
• Types of fats

  • Saturated (10%)
  • Monounsaturated (15%)
  • Polyunsaturated (10%)
• Good fats


  Monounsaturated, omega-3 & 6
• Bad fats


  Saturated, trans-monounsaturated
• Essential fatty acids


  Linoleic acid (omega-6) and linolenic acid (omega-3)
• Olestra


  Sucrose polyester, reduces absorption of cholesterol and fat-soluble vitamins
• Triacylglycerol hydrolysis

  1. Complete (all 3 fatty acids removed)

  2. Partial (one or more fatty acids remain attached to glycerol)

  
• Saponification


  Reaction of fats/oils with an alkaline solution eg (NAOH)to produce glycerol and fatty acid salts (soaps)
• Cleansing action of Soap

  related to the structure of carboxylate ions with FAS salts “ sodium stearate” ( exhibit dual polarity)
• Micelle


  Spherical cluster of soap molecules, with polar heads on the surface and nonpolar tails in the interior
• Hydrogenation


  Addition of hydrogen across double bonds to increase saturation (double bonds converted to single bonds)
• Phospholipids


  Contain one or more fatty acids, a phosphate group, and a platform molecule (glycerol or sphingosine)
• Glycerophospholipids


  Contain two fatty acids and a phosphate group esterified to a glycerol molecule
• Lecithin “Phosphatidylcholine”


  Waxy solid that forms a colloidal suspension in water, egg yolks and soybeans are good dietary source, acts as an emulsifier. lower choles
• Cholesterol


  C27 steroid, precursor for other steroid-based lipids, biosynthesized in the liver and intestine
• Atherosclerosis


  Buildup of plaque on artery walls, caused by high blood cholesterol, reduces blood flow to the heart (Heart attack)
• Cell membrane


  A Lipid bilayer structure that separates the cell's aqueous interior from the external aqueous environment controls movement of substances in and out of the cell
• Membrane proteins


  Responsible for moving substances (nutrients, electrolytes) and acting as receptors for hormones and neurotransmitters
• Emulsifier


  Substance that can disperse and stabilize water-insoluble substances in aqueous solution
• Bile


  Mixture of cholesterol derivatives secreted by the liver, stored in the gallbladder, and released into the small intestine to aid in lipid digestion
• Hormone


  Chemical messenger produced by ductless glands, includes steroid hormones (sex hormones, adrenocorticoids) and eicosanoids
• Types of steroid hormones


  • Estrogens (female sex hormones)
  • Progestins (pregnancy hormones)
  • Androgens (male sex hormones)
• Eicosanoids


  Hormone-like substances derived from arachidonic acid, include prostaglandins, thromboxanes, and leukotrienes