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4 ipids lecture 4 siham


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4 ipids lecture 4 siham

  1. 1. Principle of Biochemistry 4-Lipids Course code: HFB324 Credit hours: 3 hours Dr. Siham Gritly Dr. Siham Gritly 1
  2. 2. Fatty acids Dr. Siham Gritly 2
  3. 3. Terms to be learned• Triacylglycerol three fatty acids esterified to glycerol• cis-C=C double bond; the hydrogens on each of the two carbon atoms are on the same side of the C=C plane (as opposed to trans-C=C bonds in which the hydrogen atoms are on opposite sides)• essential fatty acids; polyunsaturated fatty acids; synthesized by plants but not by mammals• fatty acid; unbranched hydrocarbon chain with a carboxylic acid functional group at one end and acyl group at the other end (CH3)• Lipoprotein; protein with covalently attached lipids Dr. Siham Gritly 3
  4. 4. • Bilayers; two lipid layers stacked so that the hydrocarbon chains face each other, and the head groups face out and interact with water• Liposome lipid bilayers forming small vesicles in aqueous solution• Micelle aggregation of lipids in aqueous solution• phospholipids (or glycerophospholipids) major components of cell membrane; two fatty acids and phosphoric acid esterified to glycerol (CH2OH—CHOH—CH2OH)• polyunsaturated (fatty acid) fatty acid containing more than one C=C double bond Dr. Siham Gritly 4
  5. 5. • saturated (fatty acid); fatty acid containing no double bonds• Amphipathic; a molecule that has a polar region at one end location and a nonpolar region at another• Sphingolipids; complex lipids with sphingosine, a C18 amino alcohol, as backbone; found predominantly in nerve and brain tissue Dr. Siham Gritly 5
  6. 6. Lipids fats, oils, steriod and waxes• Lipids are long hydrocarbon molecules• Lipids are chemical compound naturally occurring substance; consist of carbon, hydrogen, and oxygen,• widely found in plant and animal kingdoms.• A molecule of dietary fat consists of several fatty acids (containing long chains of carbon and hydrogen atoms), bonded to a glycerol. They are typically found as triglycerides (three fatty acids attached to one glycerol backbone). Dr. Siham Gritly 6
  7. 7. Classification of fats according to National Academy of Sciences• Total fat, provide 20-35 % of total energy intake• Saturated fatty acids, risk of (Coronary Heart Disease CHD) milk fat, coconut• Cis monounsaturated fatty acids, (olive oil) prevent (CHD), peanut oil• Cis polyunsaturated fatty acids of two type health benefit; fish oil, sunflower oil, corn oil, fish oil• 1-Omega 6 fatty acids• 2-Omega 3 fatty acids• Trans fatty acids, risk of (CHD), margin, shortening Dr. Siham Gritly 7
  8. 8. Common properties of lipids• Insoluble in water; Most lipids are strictly nonpolar and hydrophobic, so they dissolve in nonpolar substances, such as ether, chloroform and benzene.• Lipids are heterogeneous group of compounds related more by their physical rather than by chemical properties• Lipids contain large regions of just carbon and hydrogen, as carbon-carbon bonds and carbon- hydrogen bonds Dr. Siham Gritly 8
  9. 9. • Stored in adipose tissues (triacylglycerols)• Related health problems such as obesity, atherosclerosis• the proportion of oxygen is low, so lipids are mostly hydrocarbons• The chemical structure of fats and oils, the most common lipids, is based on fatty acid building blocks and an alcohol, glycerol• Fats are "hard" or solid at room temperature• Oils are liquids at room temperature Dr. Siham Gritly 9
  10. 10. major functions of lipids in human body;• They serve as structural components of biological membranes, cellular constituents (lipoproteins)• *main source of energy, provide the body with 2/3 of energy (9 kal) They provide energy reserves, in the form of triacylglycerols• *main source of fat soluble vitamins A, K, E D• *protection against traumatic injury an shock• *maintain body temperature• Electrical insulator Dr. Siham Gritly 10
  11. 11. Classification of lipids• Simple lipids;-ester of fatty acid and alcohols• 1-fats; ester of fatty acids with glycerol• 2-waxes; ester of fatty acids with monohyri alcohol• Complex lipids;- ester of fatty acid containing additional to alcohol and fatty acids other groups• 1-phospholipids; containing phosphoric acid and nitrogen containing bases such as glycerophospholipid and sphingphospholipids Dr. Siham Gritly 11
  12. 12. • 2-glycolipids; containing fatty acid, sphingosine and carbohydrates• 3-other complex lipid; lipoproteins• Derived lipids;- include glycerol, steroid, alcohol in addition to glycerol and sterols Dr. Siham Gritly 12
  13. 13. Fatty Acids (FA)• Fatty acids are long-chain hydrocarbon molecules containing a carboxylic acid• The numbering of carbons in fatty acids begins with the carbon of the carboxylate group. Dr. Siham Gritly 13
  14. 14. Fatty acids structure• Fatty acids consists of a carboxyl group attached to a long hydrocarbon chain and methyl group (CH3) at the other end CH3(CH2)nCOOH Dr. Siham Gritly 14
  15. 15. • Essential fatty acids and nonessential• essential fatty acids; that they must be provided in the diet.• plants are capable of synthesizing linoleic and α-linolenic acid, humans can acquire these fats by consuming a variety of plants or else by eating the meat of animals that have consumed these plant fats.• These two essential fatty acids are also referred to as omega fatty acids. The use of the Greek omega, ω, refers to the end of the fatty acid opposite to that of the –COOH group.• Linoleic acid is an omega-6 PUFA and α-linolenic is an omega-3 PUFA Dr. Siham Gritly 15
  16. 16. The carbon chains of fatty acids can vary in 3 ways• 1-The number of carbons in the chain or the Length of chain in fatty acid• 4 – 22 carbons long• Short chains are more soluble• Short chains are more easily broken down• Short chains oxidize more easily Dr. Siham Gritly 16
  17. 17. • 2-Degree of saturation. The extent to which the chain is saturated with hydrogen• Saturated• Monounsaturated• Polyunsaturated• Most plant fats are unsaturated,• Fish oils are unsaturated• Other animal fats tend to be saturated Dr. Siham Gritly 17
  18. 18. • 3-The shape of the chain (straight or bent)• The shape of carbon chain varies with saturation• Saturated and trans fatty acids have straight carbon chain Dr. Siham Gritly 18
  19. 19. Nomenclature of fatty acids• 1-Fats may be classified as saturated or unsaturated depending on the structure of the fatty acids involved.• 2-delta ∆ and omega ω systems• 3-cis and trans geometric isomerisms Dr. Siham Gritly 19
  20. 20. Saturated and unsaturated fatty acids• Saturated acids end in; anoic• Unsaturated fatty acid end in; enoic• Saturated fatty acids; containing no double bond. Based on acetic acid—CH3-COOH where CH2 is added between methyl group and carboxylic acid CH3-CH2-CH2------COOHEg. Stearic acid CH3(CH2)14COOHPalmitic acidSaturated fatty acids of less than eight carbon atoms are liquid at physiological temperature Dr. Siham Gritly 20
  21. 21. • Saturated fatty acids: – Lauric acid 12:0 – Myristic acid 14:0 Palmitic acid – Palmitic acid 16:0 – Stearic acid 18:0 Dr. Siham Gritly 21
  22. 22. • Unsaturated fatty acids; contain one or more double bond• Eg. Oleic acid CH3(CH2)7CH=CH(CH2)COOH• Linolenic acid 18:2• Mono-ployunsaturated fatty acids• Unsaturated fatty acids: – Palmitoleic acid 16:1 – Oleic acid 18:1 Dr. Siham Gritly 22
  23. 23. saturated and unsaturated fatty acids CH3(CH2)14COOH CH3(CH2)7CH=CH(CH2)COOH Dr. Siham Gritly 23
  24. 24. Mono-unsaturated fatty acidcontain one carbon double bond Dr. Siham Gritly 24
  25. 25. Polyunsaturatedtwo or more carbon atoms are double bonded, Dr. Siham Gritly 25
  26. 26. delta ∆ and omega ω systems• Delta and omega systems are other nomenclature of fatty acids• The delta ∆ system the notation describe the chain length and the number and position of the double bonds• The linoleic acid notation is 18:2 ∆9, 12• This means 18 carbon in the chain, 2 double bond at position 9 and 12• In delta numbering start from the carboxyl end of the fatty acid Dr. Siham Gritly 26
  27. 27. delta ∆ and omega ω systemsα-Linolenic acid (ALA) 18:3Δ9,12,15 (no-3) Essential fatty acid; An omega-3 polyunsaturated fatty acid Arachidonic acid 20:4Δ5,8,11,14 An omega- 6 polyunsaturated fatty acid Precursor for eicosanoid synthesis Dr. Siham Gritly 27
  28. 28. • Omega system ω counts from the methyl end of fatty acid hydrocarbon chain; the notation for linoleic acid is 18:2 ω 6 or 18:2 n 6• This means that carbon number of linoleic acid is 18 and 2 indicates the number of double bond in position 6 counting from methyl group end of the carbon chain• The suggestion is that; The double bond in fatty acid always separated by three carbon so if the location of double bond of omega number one known the other double bond will be known Dr. Siham Gritly 28
  29. 29. • Some examples;-• Palmitoleic acid 16:1 ∆9 or 16:1 ω 7 or (n-7)• Oleic acid 18:1 ∆9 (n-9)• α-Linolenic acid (ALA) 18:3Δ9,12,15• Linoleic acid 18:2 ∆9, 12 (n-6)• Arachidonic acid 20:5 ∆5,8,11,14 (n-6)• Eicosapentaenoic acid 20:5 ∆5, 8, 11 14, 17 (n or ω3• Docosahexaenoic acid 22:6 ∆4,7,10,13,16,19 Dr. Siham Gritly 29
  30. 30. Omega-3 (ω3) and omega-6 (ω6) fatty acids• Omega-3 (ω3) and omega-6 (ω6) fatty acids are unsaturated "Essential Fatty Acids" (EFAs) that need to be included in the diet because the human metabolism cannot create them from other fatty acids Alpha-linolenic acid is an omega-3 fatty acid because it has a double bond three carbons away from the "omega" carbon Dr. Siham Gritly 30
  31. 31. Physiologically Relevant Fatty Acids adapted from 1996–2012, LLC | info @ NumericalSymbolCommon Struture Comments Name Often found attached to theMyristic acid N-term. of plasma membrane-associated 14:0 cytoplasmic proteinsPalmitic acid End product of mammalian fatty acid synthesis 16:0 Stearic acid18:0 Dr. Siham Gritly 31
  32. 32. Physiologically Relevant Fatty Acidsadapted from 1996–2012, LLC | info @ themedicalbiochemistrypage.orgOleic acid An omega-9 monounsaturated fatty acid 18:1Δ9Linoleic acid Essential fatty acid An omega-6 polyunsaturated 18:2Δ9,12 fatty acid Dr. Siham Gritly 32
  33. 33. Physiologically Relevant Fatty Acids adapted from 1996–2012, LLC | info @ α-Linolenic Essential fatty acid acid (ALA) An omega-3 polyunsaturated fatty acid 18:3Δ9,12,15 An omega-6 polyunsaturatedArachidonic acid fatty acid Precursor for eicosanoid 20:4Δ5,8,11,14 synthesisEicosapentaenoi An omega-3 polyunsaturated c acid (EPA) fatty acid enriched in fish oils 20:5Δ5,8,11,14,17Docosahexaenoi An omega-3 polyunsaturated c acid (DHA) fatty acid enriched in fish oils22:6Δ4,7,10,13,16,19 Dr. Siham Gritly 33
  34. 34. More examples Dr. Siham Gritly 34
  35. 35. Orientation of Cis and trans bond of unsaturated fatty acids• The steric geometry of unsaturated fatty acids can also vary such that the acyl groups can be oriented on the same side or on opposite sides of the double bond.• A cis configuration; hydrogen atoms are on the same side of the double bond. The more double bonds the chain has in the cis configuration, the less flexibility it has• cis bonds limit the ability of fatty acids to be closely packed, and therefore could affect the melting temperature of the membrane or of the fat Dr. Siham Gritly 35
  36. 36. • A trans configuration, means that the next two hydrogen atoms are bound to opposite sides of the double bond. As a result, they do not cause the chain to bend much, and their shape is similar to straight saturated fatty acids Dr. Siham Gritly 36
  37. 37. Cis Configuration andTrans Configuration When the acyl groups are both on the same side of the doublebond it is referred to as a cis bond, such as is the case for oleicacid (18:1).When the acyl groups are on opposite sides the bond istermed trans such as in elaidic acid, the trans isomer of oleicacid Cis Configuration Trans Configuration Dr. Siham Gritly 37
  38. 38. Trans (Elaidic acid) the trans isomer of oleic acidElaidic acid is the principal trans unsaturated fatty acid often found in partially hydrogenated vegetable oils Dr. Siham Gritly 38
  39. 39. Cis Oleic acidis a cis unsaturated fatty acid that has one double bond, "bend or curve. it comprises 55–80% of olive oil Dr. Siham Gritly 39
  40. 40. Glycerol C3H8O3• Glycerol has three hydroxyl group attached to each C atom ( alcohol) that are responsible for its solubility in water• The glycerol backbone is central to all lipids known as triglycerides Dr. Siham Gritly 40
  41. 41. Lipids and fats present in the body in three different forms• 1-neutral fats (triglycerides)• 2-cholesterol (present only in animal origin)• 3-phospholipids (largest lipid components in the body) Dr. Siham Gritly 41
  42. 42. 1-Triglycerides• Triglycerides are the main dietary fats in human body. It is a naturally occurring ester of three fatty acids and glycerol that is the chief constituent of fats and oils• Triglycerides are alcohol glycerol (hydroxyl group HO-) and three fatty acids (carboxyl group COOH). Dr. Siham Gritly 42
  43. 43. • In triglycerides, the hydroxyl groups of the glycerol join the carboxyl groups of the fatty acid to form ester bonds• Ester bond a compound formed from an alcohol and an acid by removal of water Dr. Siham Gritly 43
  44. 44. Basic Structure of TriacylglyceridesTriglycerides consists of three fatty acids and glycerol Dr. Siham Gritly 44
  45. 45. • The main fatty acids ;• 1-stearic acid a (saturated fatty acid)• 2-oleic acid (unsaturated one double bond, olive)• 3-palmitic acid (saturated, poultry, beef, milk, palm oil) Dr. Siham Gritly 45
  46. 46. Lipids are stored as triacylglycerol in adipose tissues , three fatty acids are joined to glycerol by an ester linkage Dr. Siham Gritly 46
  47. 47. triglyceride Dr. Siham Gritly 47
  48. 48. One molecule of the alcohol, glycerol Attached to the glycerol(by dehydration synthesis) are 3 fatty acids. The fatty acidsdetermine the characteristics or properties of the fat. The bondformed between the –OHs of the alcohol and the carboxylCOOH of the fatty acid is an ester bond Dr. Siham Gritly 48
  49. 49. 2-cholesterol• *Are member of groups called sterols, it is alcohol found only in tissues and cells of animals origin.• Sterols (Steroids) are composed of hydrocarbon chains with four interconnected rings. Dr. Siham Gritly 49
  50. 50. Cholesterol is a lipid (fat) which is produced by theliver. Cholesterol is vital for normal body function.Every cell in our body has cholesterol in its outer layer Dr. Siham Gritly 50
  51. 51. • *main function of cholesterol;• It enter in the formation of bile acids,• *Essential component of the structural membranes of all cells especially brain and nerve cells• *They form a part of certain enzymes• *Enter in the formation of steroid hormones such as esterogens, progesterone and testosterones• *Enter in the formation of vitamin D. Dr. Siham Gritly 51
  52. 52. The structure of sterols is very different from that of the longcarbon chains seen in fatty acids and phospholipids.The carbons in the structure of sterol are mostly arranged in manyrings Dr. Siham Gritly 52
  53. 53. steroid hormonesesterogens, progesterone and testosterones Dr. Siham Gritly 53
  54. 54. 3-phospholipids• *phospholipids are any lipids containing phosphorus. they are the largest lipid components of the body after triglycerides. Most phospholipids additional to phosphate containing choline• *they form in all cells of the body• *in plasma, they are present in combination with proteins and lipoproteins, which evolved in transport of fat and cholesterol Dr. Siham Gritly 54
  55. 55. • *they form part of certain enzymes• *main constituents of all cell membranes• Phospholipids; a group called CHNOPS, or the six elements of life:• Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur Dr. Siham Gritly 55
  56. 56. The basic structure of phospolipidsphospholipids are similar to fats, except they contain aphosphorous group and two fatty acids instead of three Dr. Siham Gritly 56
  57. 57. Functions of phospholipids• 1. Act as building blocks of the biological cell membranes in almost all organisms, form the outer cell membrane and help the cell maintain its internal structures. 2. Participate in the transduction of biological signals across the membrane. 3. Act as efficient store of energy as with triglycerides. . Dr. Siham Gritly 57
  58. 58. • 4. Play an important role in the transport of fat between gut and liver in mammalian digestion. 5. An important source of acetylcholine which is the most commonly occurring neurotransmitter substance Peripheral nervous system (PNS) and central nervous systems (CNS) occurring in mammals Dr. Siham Gritly 58
  59. 59. Phospolipids; consisting of a water-soluble head and a fat-soluble tailContain phosphorous Component of cell membranes Serve asemulsifiers (allow fats and water to mix and travel in and out ofcells into watery fluid on both sides Dr. Siham Gritly 59
  60. 60. example of phospholipids in the body• -lecithin; neurotransmitter consist of glycerol, fatty acids, phosphoric acid and cholin (nitrogen-containing base). found in liver, egg yolk, soy beans. the main function; transport and utilization of fatty acids with the action of enzyme as well as it prevent mental retardation.• *cephalins; for blood clotting (thromboplastin)• *sphingomyelins; nerve tissues and brain, function act as insulator around the verve fibers, found in egg yolk, liver.• *glycolipids; serve tissues, cell membranes and help in fat transport. Dr. Siham Gritly 60
  61. 61. The structure of phospholipids is very similar to thatof triglycerides, except a fatty acid is replaced with acompound that contains the mineral phosphorus andoften has nitrogen attached Dr. Siham Gritly 61
  62. 62. The benefit of the phospholipid structure is that thephosphate region makes the molecule highly amphipathic,ideal for the cell membrane structure Hydrophilic portion in the phosphate regionHydrophobic portion in the fatty acid Dr. Siham Gritly 62
  63. 63. Phospholipids are major component of all cell membrane as they can form lipid bilayers. Mostphospholipids contain a diglyceride a phosphate group and choline Dr. Siham Gritly 63
  64. 64. Dr. Siham Gritly 64
  65. 65. Phospholipid bilayers form the protective layer around cells Dr. Siham Gritly 65
  66. 66. Exercise 3; Fat digestionA. DigestionB. EmulsificationC. Absorption Dr. Siham Gritly 66
  67. 67. References• Murry K. Robert, Granner K. daryl, Mayes A. peter, Rodwell W. Victor (1999). Harpers Biochemistry. Appleton and Lange , twent fifth edition• © 1996–2012, LLC | info @• Sareen Gropper, Jack Smith and James Groff, Advanced Nutrition and Human Metabolism, fifth ed. WADSWORTH• Melvin H Williams 2010; Nutrition for Health, Fitness and Sport. 9th ed, McGraw Hill•• Heymsfield, SB.; Baumgartner N.; Richard and Sheau-Fang P. 1999. Modern Nutrition in Health and Disease; Shils E Maurice, Olson A. James, Shike Moshe and Ross A. Catharine eds. 9th edition• Guyton, C. Arthur. 1985. Textbook of Medical Physiology. 6th edition, W.B. Company Dr. Siham Gritly 67
  68. 68. • Lehninger. Principles of bochemistry. by Nelson and Cox, 5th Edition; W.H. Freeman and Company• Emsley, John (2011). Natures Building Blocks: An A-Z Guide to the Elements (New ed.). New York, NY: Oxford University Press. ISBN 978-0-19-960563-7.• Koppenol, W. H. (2002). "Naming of New Elements (IUPAC Recommendations 2002)" (PDF). Pure and Applied Chemistry 74 (5): 787–791. doi:10.1351/pac200274050787.• What Are the Primary Functions of Phospholipids? | phospholipids_.html#ixzz2FzYc7HnG Dr. Siham Gritly 68
  69. 69. • Campbell, Neil A.; Brad Williamson; Robin J. Heyden (2006). Biology: Exploring Life. Boston, Massachusetts: Pearson Prentice Hall• A. Burtis, Edward R. Ashwood, Norbert W. Tietz (2000), Tietz fundamentals of clinical chemistry• Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. pp. 52–59• Maitland, Jr Jones (1998). Organic Chemistry. W W Norton & Co Inc (Np). p. 139. ISBN 0- 393-97378-6.• Nelson DL, Cox MM (2005). Lehningers Principles of Biochemistry (4th ed.). New York, New York: W. H. Freeman and Company.• Matthews, C. E.; K. E. Van Holde; K. G. Ahern (1999) Biochemistry. 3rd edition. Benjamin Cummings.• Dr. Siham Gritly 69
  70. 70. Dr. Siham Gritly 70