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• Lipids


  They are not defined by a particular functional group, thus they have a variety of structures and functions
• Lipids


  • They contain many nonpolar C—C and C—H bonds and few polar bonds resulting in their water insolubility
• Lipids


  • Soluble in organic solvents or non-polar solvents
  • Insoluble in water
  • Heterogeneous group of compounds
  • Related more by their physical than by their chemical properties
  • Pure lipids are colorless with bland odor and taste
  • Poor conductors of heat and electricity
  • Serve as excellent insulators for the body, slowing the loss of heat through the skin
  • When heated strongly, undergoes decomposition forming acrid flammable vapors
  • When ignited, they burn with a sooty flame
• Functions of Lipids


  • Major source of energy for the body
  • Provide the hydrophobic barrier that permits the partitioning of the aqueous contents of cells and subcellular structures
  • Some fat-soluble vitamins have regulatory or coenzyme functions, and the prostaglandins and steroid hormones play major roles in the control of the body's homeostasis
  • Act as precursors for other lipids and play a role in the transporting other lipids in the body
  • Functions as emulsifying agents in the gastrointestinal tract
• Hydrolysis


  1. Fats and oils can be hydrolyzed in the presence of an acid, a base, or specific enzymes known as Lipase

  2. The hydrolysis of fats and oils in the presence of a base is used to make soap and is called Saponification
• Hydrogenation


  1. The double bonds in fats and oils can undergo hydrogenation

  2. Chemically, it is essentially identical to the catalytic hydrogenation reaction described for alkenes

  3. In commercial processes, the number of double bonds that are hydrogenated is carefully controlled to produce fats with the desired consistency (soft & pliable)
• Oxidation


  1. Fats and oils that are in contact with moist air at room temperature eventually undergo oxidation and hydrolysis reactions that cause them to turn rancid, acquiring a disagreeable odor

  2. One cause of the odor is the release of volatile fatty acids by hydrolysis of the ester bonds

  3. Butter, for example, releases foul-smelling butyric, caprylic, and capric acids

  4. Microorganisms present in the air furnish lipases that catalyze this process

  5. Hydrolytic rancidity can easily be prevented by covering the fat or oil and keeping it in a refrigerator
• an be hydrolyzed in the presence of an acid, a base, or specific enzymes known?


  as Lipase
• The hydrolysis of fats and oils in the presence of a base is used to make soap and is called?

  Saponification. 
• Fats and oils that are in contact with moist air at room temperature eventually undergo?

  Oxidation
• Lipids can be classified based on their reaction with?

  water
• Can be converted into smaller molecules · These are compounds that are derived from fatty acids?

  Hydrolyzable Lipids
• what are the hydrolyzable lipids? (wtp)


  Triglycerides, phospholipids, and waxes
• · Cannot be cleaved into smaller molecules be aqueous hydrolysis?


  Nonhydrolyzable Lipids 
• what are the Nonhydrolyzable Lipids ?

  steroids, fatsoluble vitamins, eiconoids
• Simple Lipids


  Esters of fatty acids with various alcohols
• Simple Lipids

  • triglycerides
  • waxes
• Complex Lipids

  Lipids containing parts other than fatty acids and alcohol
• Complex Lipids

  • Found in cell membranes, brain, nervous tissues, myelin sheaths of nerves, and blood platelets
• Complex Lipids

  • phospholipids
  • sphingolipids
  • glycolipids
  • lipoproteins
• Derived Lipids

  These compounds are products of hydrolysis of simple and complex lipids
• Derived Lipids

  • steroids
  • prostaglandins
  • vitamins
  • hormones
• Fatty Acids


  Carboxylic acids with long, unbranched carbon chains
• Naturally occurring fatty acids have an even number of carbon atoms
• Hydrolyzable lipids


  Derived from fatty acids
• Fatty Acids


  • Apart from the Carboxylic Acid (-COOH) group, they have no functional groups, except that some do have double bonds
  • Contains a polar and a nonpolar end
• · Has no double bonds in their long hydrocarbon chains?

  Saturated Fatty Acids 
• Saturated Fatty Acids


  Have no double bonds in their long hydrocarbon chains
• Saturated Fatty Acids


  • Lauric Acid/Dodecanoic Acid (12C)
  • Myristic Acid/Tetradecanoic Acid (14C)
  • Palmitic Acid/Hexadecanoic Acid (16C)
  • Stearic Acid/Octadecanoic Acid (18C)
• Lauric Acid/Dodecanoic Acid (12C)


  CH3 – (CH2)10 – COOH
• Myristic Acid/Tetradecanoic Acid (14C)


  CH3 – (CH2)12 – COOH
• Palmitic Acid/Hexadecanoic Acid (16C)


  CH3 – (CH2)14 – COOH
• Stearic Acid/Octadecanoic Acid (18C)


  CH3 – (CH2)16 – COOH
• · Has 1 or more double bonds (generally cis) in their long hydrocarbon chains?

  Unsaturated fats
• Unsaturated Fatty Acids with one double bond?

  monounsaturated
• Unsaturated Fatty Acids with two double bond?

  Polyunsaturated
• · Have two hydrogen atoms on the same side of the double bond, which creates a kink in the structure?

  Cis Fatty Acids 
• · Have two hydrogen atoms on the opposite side of the double bond, which results in a similar structure to that of saturated fatty acid?

  Trans Fatty Acids 

  ·
• Essential Fatty Acids


  Fatty acids that cannot be produced by the body
• Essential Fatty Acids


  • Alpha-linolenic Acid (ALA)
  • Linoleic Acid (LA)