Presentation is loading. Please wait.

Presentation is loading. Please wait.

19-1 Chemistry 121 Winter 2009 LA Tech Chapter 19. Lipids Sections.

Similar presentations


Presentation on theme: "19-1 Chemistry 121 Winter 2009 LA Tech Chapter 19. Lipids Sections."— Presentation transcript:

1 19-1 Chemistry 121 Winter 2009 LA Tech Chapter 19. Lipids Sections

2 19-2 Chemistry 121 Winter 2009 LA Tech Chapter 19 19.1 Structure and Classification of Lipids 19.2 Fatty Acids: Lipid Building Blocks 19.3 Physical Properties of Fatty Acids 19.4 Energy-Storage Lipids: Triacylglycerols 19.5 Dietary Considerations and Triacylglycerols 19.6 Chemical Reactions of Triacylglycerols 19.7 Membrane Lipids: Phospholipids 19.8 Membrane Lipids: Sphingoglycolipids 19.9 Membrane Lipids: Cholesterol 19.10 Cell Membranes 19.11 Emulsification Lipids: Bile Acids 19.12 Messenger Lipids: Steroid Hormones 19.13 Messenger Lipids: Eicosanoids 19.14 Protective-Coating Lipids: Biological Waxes Chemistry at a Glance: Types of Lipids and How They Function Chemical Connections: The Fat Content of Tree Nuts and Peanuts; Artificial Fat Substitutes; The Cleansing Action of Soap; Trans Fatty Acids and Blood Cholesterol Levels; Steroid Drugs in Sports; The Mode of Action for Anti-Inflammatory Drugs

3 19-3 Chemistry 121 Winter 2009 LA Tech Lipids A heterogeneous class of naturally occurring organic compounds classified together on the basis of common solubility properties A heterogeneous class of naturally occurring organic compounds classified together on the basis of common solubility properties insoluble in water soluble in aprotic organic solvents including diethyl ether, dichloromethane, and acetone Lipids include Waxes triglycerides phospholipids Prostaglandins cholesterol, steroid hormones, and bile acids fat-soluble vitamins

4 19-4 Chemistry 121 Winter 2009 LA Tech Structure and Classification of Lipids Lipids that are ester or amides of fatty acids: Waxes – are carboxylic acid esters where both are carboxylic acid esters where both R groups are long straight hydrocarbon chain. R groups are long straight hydrocarbon chain. Performs external protective functions. Performs external protective functions. Triglycerides– are carboxylic acid are carboxylic acid triesters of Glycerols. They are a major source of biochemical energy. Glycolipids – amides derived from sphingosine, contain polar carbohydrate groups. On the cell surface, they connect with intracellular messengers. Glycerophopholipids – triesters of glycerols that contain charged phosphate diesters. They help to control the flow of molecules into and out of cells. Sphingomyelins – amides derived from an amino alcohol, also contain charged amino alcohol, Phosphate diester groups. They are essential to the structure of cell membranes. Lipids that are not esters or amides: Steroids – They performs various functions They performs various functions such as hormones and contributes to the structure of cell membranes. Eicosanoids – They are carboxylic acids that are a special type of intracellular chemical messengers.

5 19-5 Chemistry 121 Winter 2009 LA Tech Wax esters are fatty acids esterified to long-chain saturated or monoenoic (one double bond) alcohols. They are carboxylic acid esters where both are carboxylic acid esters where both R groups are long straight hydrocarbon chain. R groups are long straight hydrocarbon chain. They performs external protective functions. Performs external protective functions. Beeswax Spermaciti: sperm whale wax

6 19-6 Chemistry 121 Winter 2009 LA Tech Bee’s wax Spermaceti source Carnauba wax source

7 19-7 Chemistry 121 Winter 2009 LA Tech Triglycerides

8 19-8 Chemistry 121 Winter 2009 LA Tech Properties of Fats and Oils Oils: A mixture of triglycerides that is liquid because it contains a high proportions of unsaturated fatty acids. Fats : A mixture of triglycerides that is solid because it contains a high proportions of saturated fatty acids.

9 19-9 Chemistry 121 Winter 2009 LA Tech Physical properties of Triglycerides Depends on their fatty acid components melting point increases as the number of carbons in their hydrocarbon chains increases and as the number of double bonds decreases oilstriglycerides rich in unsaturated fatty acids are generally liquid at room temperature and are called oils fatstriglycerides rich in saturated fatty acids are generally semisolids or solids at room temperature and are called fats

10 19-10 Chemistry 121 Winter 2009 LA Tech Triglycerides The lower melting points of triglycerides rich in unsaturated fatty acids are related to differences in their three-dimensional shape hydrocarbon chains of saturated fatty acids can lie parallel with strong dispersion forces between their chains; they pack into well-ordered, compact crystalline forms and melt above room temperature because of the cis configuration of the double bonds in unsaturated fatty acids, their hydrocarbon chains have a less ordered structure and dispersion forces between them are weaker; these triglycerides have melting points below room temperature

11 19-11 Chemistry 121 Winter 2009 LA Tech Reduction of Triglycerides hardeningthe process of converting fats to oils is called hardening and involves catalytic reduction of some or all of an oil’s carbon-carbon double bonds in practice, the process is controlled to produce a fat of a desired consistency the resulting fats are sold for cooking (Crisco, Spry, and others) margarine and other butter substitutes are produced by partial hydrogenation of polyunsaturated oils derived from corn, peanuts, and soybeans because catalytic hydrogenation is to some degree reversible, hardening results in the isomerization of some cis-fatty acids to trans-fatty acids; trans fatty acids are to be avoided as much as possible

12 19-12 Chemistry 121 Winter 2009 LA Tech Triglycerides An ester of glycerol with three fatty acids

13 19-13 Chemistry 121 Winter 2009 LA Tech Soaps and Detergents Natural soaps are prepared by boiling lard or other animal fat with NaOH, in a reaction called saponification (Latin, sapo, soap)

14 19-14 Chemistry 121 Winter 2009 LA Tech Soaps and Detergents Soaps clean by acting as emulsifying agents the long hydrophobic hydrocarbon chains of soaps are insoluble in water and tend to cluster in such a way as to minimize their contact with water the polar hydrophilic carboxylate groups tend to remain in contact with the surrounding water molecules driven by these two forces, soap molecules spontaneously cluster into micelles MicelleMicelle: a spherical arrangement of organic molecules in water clustered so that their hydrophobic parts are buried inside the sphere and their hydrophilic parts are on the surface of the sphere and in contact with water

15 19-15 Chemistry 121 Winter 2009 LA Tech Soaps and Detergents when soap is mixed with water-insoluble grease, oil, and fat stains, the nonpolar parts of the soap micelles “dissolve” nonpolar dirt molecules and they are carried away in the polar wash water

16 19-16 Chemistry 121 Winter 2009 LA Tech Soaps Soaps form water-insoluble salts when used in water containing Ca(II), Mg(II), and Fe(III) ions (hard water)

17 19-17 Chemistry 121 Winter 2009 LA Tech Synthetic Detergents The design criteria for a good detergent are a long hydrocarbon tail of 12 to 20 carbons a polar head group that does not form insoluble salts with Ca(II), Mg(II), or Fe(III) ions the most widely used synthetic detergents are the linear alkylbenzenesulfonates (LAS) also added to detergent preparations are foam stabilizers, bleaches, and optical brighteners

18 19-18 Chemistry 121 Winter 2009 LA Tech Fatty Acids A long, unbranched chain carboxylic acid A long, unbranched chain carboxylic acid nearly all have an even number of carbon atoms, most between 12 and 20, in an unbranched chain the three most abundant are palmitic acid (16:0), stearic acid (18:0), and oleic acid (18:1) in most unsaturated fatty acids, the cis isomer predominates; the trans isomer is rare unsaturated fatty acids have lower melting points than their saturated counterparts; the greater the degree of unsaturation, the lower the melting point

19 19-19 Chemistry 121 Winter 2009 LA Tech Fatty Acids The most abundant fatty acids

20 19-20 Chemistry 121 Winter 2009 LA Tech Saturated Fatty Acids

21 19-21 Chemistry 121 Winter 2009 LA Tech

22 19-22 Chemistry 121 Winter 2009 LA Tech Unsaturated Fatty Aicds

23 19-23 Chemistry 121 Winter 2009 LA Tech Saturated/unsturated fatty acids

24 19-24 Chemistry 121 Winter 2009 LA Tech Saturated/unstaureated Mixtures

25 19-25 Chemistry 121 Winter 2009 LA Tech Fatty Acids the greater the degree of unsaturation the lower the melting point

26 19-26 Chemistry 121 Winter 2009 LA Tech

27 19-27 Chemistry 121 Winter 2009 LA Tech What are "Omega" series fatty acids? Scientists differentiate fatty acids by the characteristics of their molecules. The two principal essential fatty acids are Omega-6 (n-6) series and the Omega-3(n-3) series. The number indicates the position of the first double carbon bond when counting from a specified end of the molecule.

28 19-28 Chemistry 121 Winter 2009 LA Tech Essential Fatty Acids Fatty acids that cannot be produced by the body and are necessary for proper metabolism. The OMEGA 6 and OMEGA 3 fatty acids are referred to as Essential Fatty Acids (EFA).

29 19-29 Chemistry 121 Winter 2009 LA Tech Phospholipids Phospholipids are the second most abundant group of naturally occurring lipids they are found almost exclusively in plant and animal membranes, which typically consist of 40% to 50% phospholipids and 50% to 60% proteins the most abundant phospholipids are derived from phosphatidic acid, a molecule in which glycerol is esterified with two fatty acids and one phosphoric acid further esterification with a low-molecular weight alcohol gives a phospholipid the three most abundant fatty acids in phosphatidic acids are palmitic acid (16:0), stearic acid (18:0), and oleic acid (18:1)

30 19-30 Chemistry 121 Winter 2009 LA Tech Phospholipids Phosphate(PO 4 )-containing molecules with structures related to the triglycerides are aclled Glycerophopholipids E.g. Phosphatidycholine (lecithin) E.g. Phosphatidycholine (lecithin)

31 19-31 Chemistry 121 Winter 2009 LA Tech Examples of glycerophospholipids Name Phosphatidyl choline (lecithin) Phosphatidyl ethanolamine (cephalin)

32 19-32 Chemistry 121 Winter 2009 LA Tech Phospholipids A phosphatidate and a phospholipid

33 19-33 Chemistry 121 Winter 2009 LA Tech Phospholipids

34 19-34 Chemistry 121 Winter 2009 LA Tech Phosphatidycholine (lecithin)

35 19-35 Chemistry 121 Winter 2009 LA Tech Phospholipids low-molecular weight alcohols in phospholipids

36 19-36 Chemistry 121 Winter 2009 LA Tech Lipid Bilayer When placed in aqueous solution, phospholipids spontaneously form a lipid bilayer polar head groups lie on the surface, giving the bilayer an ionic coating nonpolar fatty acid hydrocarbon chains lie buried within the bilayer This self-assembly is driven by two noncovalent forces hydrophobic effectshydrophobic effects, which result when nonpolar hydrocarbon chains cluster to exclude water molecules electrostatic interactionselectrostatic interactions, which result when polar head groups interact with water and other polar molecules in the aqueous environment

37 19-37 Chemistry 121 Winter 2009 LA Tech Plasma membrane Planar lipid bilayers Biological membranes are bilipid layers. In a real cell the membrane phospholipids create a spherical three dimensional lipid bilayer shell around the cell. However, they are often represented two-dimensionally as: In a real cell the membrane phospholipids create a spherical three dimensional lipid bilayer shell around the cell. However, they are often represented two-dimensionally as: Passive tranport Active transport

38 19-38 Chemistry 121 Winter 2009 LA Tech Biological Membranes Fluid mosaic model: a biological membrane consists of a phospholipid bilayer with proteins, carbohydrates, and other lipids embedded on the surface and in the bilayer fluidfluid signifies that the protein components of membranes “float” in the bilayer and can move freely along the plane of the membrane mosaicmosaic signifies that the various components of the membrane exist side by side, as discrete units rather than combining to form new molecules and ions

39 19-39 Chemistry 121 Winter 2009 LA Tech Fluid-Mosaic Model

40 19-40 Chemistry 121 Winter 2009 LA Tech Prostaglandins Essential fatty acids in the cell membranes produce prostaglandins. Prostaglandins regulate bodily functions in the heart, kidneys, liver, lungs, brain, nerves and the immune system.

41 19-41 Chemistry 121 Winter 2009 LA Tech Types of Prostaglandins In human beings, there are three families of prostaglandins, each of which is derived from a different fatty acid. Prostaglandin PG PGE 1 PGF 1 PGE 2 PGF 2 Eicosanoids Thromboxane A 2 Leukotriene B 4

42 19-42 Chemistry 121 Winter 2009 LA Tech Prostaglandins Prostaglandins: a family of compounds that have the 20-carbon skeleton of prostanoic acid

43 19-43 Chemistry 121 Winter 2009 LA Tech Prostaglandins Prostaglandins are not stored in tissues as such, but are synthesized from membrane-bound 20- carbon polyunsaturated fatty acids in response to specific physiological triggers one such polyunsaturated fatty acid is arachidonic acid

44 19-44 Chemistry 121 Winter 2009 LA Tech Prostaglandins among the prostaglandins synthesized biochemically from arachidonic acid are

45 19-45 Chemistry 121 Winter 2009 LA Tech Prostaglandins the observation that PGF 2  stimulates contractions of uterine smooth muscle led to the development of synthetic PGFs that can be used for therapeutic abortions

46 19-46 Chemistry 121 Winter 2009 LA Tech Prostaglandins the PGE 1 analog, misoprostol, is used to prevent the ulceration associated with the use of aspirin-like NSAIDs

47 19-47 Chemistry 121 Winter 2009 LA Tech Eicosanoids The prostaglandins are members of an even larger family of compounds called eicosanoids, all of which contain 20 carbons and are derived from polyunsaturated fatty acids thromboxanes

48 19-48 Chemistry 121 Winter 2009 LA Tech Eicosanoids Leukotrienes found primarily in white blood cells one function is constriction of smooth muscles, especially those of the lungs

49 19-49 Chemistry 121 Winter 2009 LA Tech Eicosanoids Prostacyclin

50 19-50 Chemistry 121 Winter 2009 LA Tech Steroids A group of plant and animal lipids that have this tetracyclic ring structure

51 19-51 Chemistry 121 Winter 2009 LA TechSteroids Fats similar to, and usually synthesized from, cholesterol.

52 19-52 Chemistry 121 Winter 2009 LA Tech

53 19-53 Chemistry 121 Winter 2009 LA Tech Steroids Features common to steroids the fusion of rings is trans and each atom or group at a ring junction is axial the pattern of atoms or groups along the ring junctions is nearly always trans-anti-trans-anti-trans the steroid system is nearly flat and quite rigid most have axial methyl groups at C-10 and C-13

54 19-54 Chemistry 121 Winter 2009 LA Tech Steroids Cholesterol

55 19-55 Chemistry 121 Winter 2009 LA Tech Steroids Androgens - male sex hormones synthesized in the testes responsible for the development of male secondary sex characteristics

56 19-56 Chemistry 121 Winter 2009 LA Tech Steroids Anabolic steroid: a steroid hormone, such as testosterone, that promotes tissue and muscle growth and development

57 19-57 Chemistry 121 Winter 2009 LA Tech Steroids Estrogens: female sex hormones synthesized in the ovaries responsible for the development of female secondary sex characteristics and control of the menstrual cycle

58 19-58 Chemistry 121 Winter 2009 LA Tech Synthetic Estrogens Progesterone-like analogs are used in oral contraceptives

59 19-59 Chemistry 121 Winter 2009 LA Tech Steroids Glucocorticoid hormones synthesized in the adrenal cortex regulate metabolism of carbohydrates decrease inflammation involved in the reaction to stress

60 19-60 Chemistry 121 Winter 2009 LA Tech Steroids Mineralocorticoid hormones synthesized in the adrenal cortex regulates blood pressure and volume by stimulating the kidneys to absorb Na +, Cl -, and HCO 3 -

61 19-61 Chemistry 121 Winter 2009 LA Tech Steroids Bile acids synthesized in the liver, stored in the gallbladder, and secreted into the intestine emulsify dietary fats and aid in their absorption and digestion

62 19-62 Chemistry 121 Winter 2009 LA Tech Steroid Biosynthesis The building block from which all carbon atoms of steroids are derived is the two-carbon acetyl group of acetyl-CoA Stage 1: synthesis of isopentenyl pyrophosphate from three molecules of acetyl-CoA (Sect 16.5) Stage 2: synthesis of cholesterol Stage 3: conversion of cholesterol to other steroids

63 19-63 Chemistry 121 Winter 2009 LA Tech

64 19-64 Chemistry 121 Winter 2009 LA Tech Fat-Soluble Vitamins Vitamins are divided into two broad classes on the basis of their solubility those that are fat soluble (and hence classified as lipids those that are water soluble The fat-soluble vitamins include A, D, E, and K

65 19-65 Chemistry 121 Winter 2009 LA Tech Vitamin A (Retinol) occurs only in the animal world found in the plant world in the form of a provitamin in a group of pigments called carotenes

66 19-66 Chemistry 121 Winter 2009 LA Tech Vitamin A The best understood role of vitamin A is its participation in the visual cycle in rod cells the active molecule is retinal (vitamin A aldehyde), which forms an imine with an -NH 2 group of the protein opsin to form the visual pigment called rhodopsin the primary chemical event of vision in rod cells is absorption of light by rhodopsin followed by isomerization of the 11-cis double bond to the 11-trans configuration

67 19-67 Chemistry 121 Winter 2009 LA Tech Vitamin A isomerization of the double bond at C11-C12 is triggered by light striking rhodopsin

68 19-68 Chemistry 121 Winter 2009 LA Tech Vitamin A a group of structurally related compounds that play a role in the regulation of calcium and phosphorus metabolism the most abundant form is vitamin D 3

69 19-69 Chemistry 121 Winter 2009 LA Tech Vitamin E Vitamin E: a group of compounds of similar structure the most active is  -tocopherol vitamin E functions as an antioxidant; it traps peroxy radicals of the type HOO and ROO formed as a result of oxidation by O 2 of unsaturated hydrocarbon chains in membrane phospholipids

70 19-70 Chemistry 121 Winter 2009 LA Tech Vitamin K the name of this vitamin comes from the German word Koagulation, signifying its important role in the blood- clotting process

71 19-71 Chemistry 121 Winter 2009 LA Tech Nonglyceride Lipids Phingolipidssteroids,waxes

72 19-72 Chemistry 121 Winter 2009 LA Tech Sphingolipids: Sphingosine These lipids are based on sphingosine, are found in plants and animals, and are common in the nervous system. sphingosine

73 19-73 Chemistry 121 Winter 2009 LA Tech Sphingolipids ceramide N-acylsphingosine sphingomyelin A ceramide with phosphocholine or phosphoethanolamine as head group

74 19-74 Chemistry 121 Winter 2009 LA TechSphingoglycolipids Attachment of carbohydrates to primary -OH of ceramide Cerebrosides: contain a single moiety, principally galactose Sulfatides: sulfuric esters of galactocerebrosides Gangliosides: contain a complex oligosaccharide moiety

75 19-75 Chemistry 121 Winter 2009 LA TechSphingolipids

76 19-76 Chemistry 121 Winter 2009 LA Tech Sphingoglycolipids-2 a cerebroside These compounds are found in the cell membranes of nerve and brain cells.

77 19-77 Chemistry 121 Winter 2009 LA Tech Clinical significance of sphingolipids RRRRRR Type 0 Type A Type B GlcNAc Fucose Galactose Sialic acid (NANA) Blood groups determined by various glycolipids on RBCs

78 19-78 Chemistry 121 Winter 2009 LA Tech Estrogens They are primarily responsible for the conversion of girls into sexually-mature women. Participate in the monthly preparation of the body for a possible pregnancy. Participate in pregnancy if it occurs

79 19-79 Chemistry 121 Winter 2009 LA Tech Anabolic steroids A number of synthetic androgens promote an increase in body weight and muscle strength: popular with athletes, weight lifters, cyclists, professional football players, etc. Often these athletes take doses 100 time greater than those used in standard therapy. Such illicit use Side effects: acne, a decrease in libido, testicle size, and sperm counts to name a few.

80 19-80 Chemistry 121 Winter 2009 LA Tech Complex lipids Lipoproteins Lipoproteins are composed of a neutral core of cholesterol and triacylglycerols. Lipoproteins are composed of a neutral core of cholesterol and triacylglycerols.Glycolipids Sugar containing lipids Sugar containing lipids

81 19-81 Chemistry 121 Winter 2009 LA Tech Four major groups of plasma lipoproteins. 1. Chylomicrons 2. Very low-density lipoproteins (VLDL) 3. Low-density lipoproteins (LDL) 4. High-density lipoproteins (HDL)

82 19-82 Chemistry 121 Winter 2009 LA Tech The roles of HDL, LDL, and cholesterol. Cholesterol and lipoproteins are related plaque that causes heart attacks and most strokes. When LDL levels are low, atherosclerosis and heart attacks are almost unknown. High HDL levels are associated with a reduced risk of heart disease: "good" cholesterol

83 19-83 Chemistry 121 Winter 2009 LA TechSphingolipids These lipids are based on sphingosine, are found in plants and animals, and are common in the nervous system. sphingosine

84 19-84 Chemistry 121 Winter 2009 LA Tech Sphingolipids ceramide N-acylsphingosine sphingomyelin A ceramide with phosphocholine or phosphoethanolamine as head group

85 19-85 Chemistry 121 Winter 2009 LA TechSphingoglycolipids Attachment of carbohydrates to primary -OH of ceramide Cerebrosides: contain a single moiety, principally galactose Sulfatides: sulfuric esters of galactocerebrosides Gangliosides: contain a complex oligosaccharide moiety

86 19-86 Chemistry 121 Winter 2009 LA Tech Sphingoglycolipids-2 a cerebroside These compounds are found in the cell membranes of nerve and brain cells.

87 19-87 Chemistry 121 Winter 2009 LA Tech Clinical significance of sphingolipids RRRRRR Type 0 Type A Type B GlcNAc Fucose Galactose Sialic acid (NANA) Blood groups determined by various glycolipids on RBCs


Download ppt "19-1 Chemistry 121 Winter 2009 LA Tech Chapter 19. Lipids Sections."

Similar presentations


Ads by Google