Transcript Fatty acids
Dr. Tarek El Sewedy Department of Medical Laboratory Technology Faculty of Allied Medical Sciences Lipids and Fatty acids (1) Intended Learning Outcomes By the end of this lecture, students will learn: General structure and functions of lipids. How to write the chemical formula of fatty acids. Classification of fatty acids. Lipid Nutritional facts. Lecture Content • Lipids and fatty acids structure . • Physiological role of fatty acids. • Classification of lipids. • Nomenclature of fatty acids. • Classification of fatty acids. • Fats and diet Lipids Lipids are heterogeneous compounds composed of C,H and O and may contain P, N and S. They includes fats, waxes, phospholipids, and other physical-properties related compounds. • They have the common physical property of being: • Insoluble in water • Soluble in nonpolar solvents such as ether and chloroform. The monomers of lipids are fatty acids. Fatty acids • Fatty Acids Are Key Constituents (Monomers) of Lipids • Among the most biologically significant properties of lipids are their hydrophobic properties. • This property is mainly due to a particular component of lipids: fatty acids Structure of Fatty Acids Fatty acids are hydrocarbon chains of various lengths and degrees of unsaturation that terminate with carboxylic acid groups. a. Stearic acid (saturated) B. Oleic Acid (unsaturated) The physical characteristics of the fatty acid (e.g. number of double bonds) determine its biochemical properties (e.g. solubility, melting point) Fats containing a high proportion of saturated fatty acids, such as butter , have a relatively high melting temperature and tend to be solid at room temperature. Most vegetable oils, which contain higher levels of monounsaturated or polyunsaturated fats, are usually liquid at room temperature. Physiological role of fatty acids • First, fatty acids are building blocks of phospholipids and glycolipids. These molecules are important components of biological membranes. • Second, many proteins are modified by the covalent attachment of fatty acids, which targets them to membrane locations. • Third, fatty acids are fuel molecules. They are oxidized to meet the energy needs of a cell or organism. • Fourth, fatty acid derivatives serve as hormones and intracellular messengers. Lipids & Energy Carbohydrates = 4.1 Kcal/gm Energy source Fat=9.3 Kcal/gm 1. Classification of lipids 1. Simple 2. Complex 3. Precursor or Derived Classification of lipids • LIPIDS ARE CLASSIFIED AS SIMPLE OR COMPLEX Or DERIVED A. Simple lipids: Esters of fatty acids with various alcohols. 1. Fats: Esters of fatty acids with glycerol. 2. Waxes: Esters of fatty acids with higher molecular weight alcohols. (Fatty Acid) A. Simple lipids Esters of fatty acids with various alcohols. (Fatty Acid) O H2C OH HC OH O HO H2C C OH glycerol fatty acid H2C O C O R HC O C O R H2C O C R R triacylglycerol (Fat) Ester Bond (Simple Lipid) FAT Triacylglycerol(Triglycerides) Glycerol: Three carbon trialcohol. Fatty acids: aliphatic carboxylic acids. Could be monoglycerides, diglycerides, or triglycerides, depending on whether there are one, two, or three fatty acid chains present in the molecules. b. Complex lipids • Esters of fatty acids containing groups in addition to an alcohol and a fatty acid. • a. Phospholipids: Lipids containing, in addition to fatty acids and an alcohol, a phosphoric acid residue. • b. Glycolipids: Lipids containing a fatty acid, alcohol, and carbohydrate. • C. Other complex lipids: Lipids such as sulfolipids and Lipoproteins. Lipids in Cell Membrane (Phospholipds) 1 glycerol + 2 fatty acids + 1 phosphate group + 1 organic functional group = phospholipid Phosphate groups – Interacts with water; because the phosphate head is polar. Fatty acid ‘legs’ – Non-polar, do not interact with water and align themselves together to be protected from the water while exposing the phosphate groups to the water. C. Derived lipids • These include lipid-soluble vitamins, and hormones. Nomenclature of Fatty Acids • The name for a fatty acid is derived from the name of its parent hydrocarbon by the substitution of oic for the final e. ex. the C18 fatty acid is called octadecanoic acid because the parent hydrocarbon is octadecane (18) • The notation 18:0 denotes a C18 fatty acid with no double bonds, whereas (18:3n 9,12,15) signifies that there are three double bonds at position 9,12 and 15 of carboxyl carbon. • Carbon atoms are numbered from the carboxyl carbon (carbon No. 1). The carbon atoms adjacent to the carboxyl carbon (Nos. 2, 3, and 4) are also known as the α, β, and γ carbons, respectively, and the terminal methyl carbon is known as the ω or n-carbon I-According to number of carbon atoms Short chain 2-10 C atoms Butyric acid (4 C) long chain >10 C atoms Palmitic acid(16C) II-According to presence or absence of double bond Saturated unsaturated Palmitic acid, Butyric acid, Caproic acid, Stearic acid Monounsaturated Polyunsaturated Oleic acid C18 Nervonic acid C24 Linoleic acid C18 Linolenic acid C18 Arachidonic acid C20 SATURATED FATTY ACIDS Common Name Condensed Formula Capric CH3(CH2)8COOH Lauric CH3(CH2)10COOH Myristic CH3(CH2)12COOH Palmitic CH3(CH2)14COOH Stearic CH3(CH2)16COOH Arachidic CH3(CH2)18COOH Common Unsaturated Fatty Acids Common Names RCOOH Formula # of Double Bonds Double Bond Position Palmitoleic C15H29COOH 1 9 Oleic C17H33COOH 1 9 Linoleic C17H33COOH 2 9, 12 Linolenic C17H31COOH 3 9, 12, 15 Arachidonic C19H31COOH 4 5, 8, 11, 14 Unsaturated fatty acid are classified into Cis trans • Cis and trans are terms that refer to the arrangement of the two hydrogen atoms bonded to the carbon atoms involved in a double bond. In the cis arrangement, the hydrogens are on the same side of the double bond. In the trans arrangement, the hydrogens are on opposite sides of the double bond III-According to nutrition state Essential Non essential Polyunsaturated Linoleic acid C18 Arachidonic acid C20 Sarurated FA Monounsaturated FA 1-Non essential fatty acids: They can be synthesized in the human body All saturated and monounsaturated FA's Ex: Palmitoleic acid ( 16:1n;∆9) higher concentrations in the liver Ex: Oleic acid; ( 18:1n;∆9) majority of olive oil CH3(CH2)5CH=CH(CH2)7COOH 2- Essential fatty acids Polyunsaturated fatty acids Need to get them from diet because the body cannot manufacture them. Alpha linolenic acid (18:3n;∆9,12,15): is the so-called "parent" fatty acid for the omega 3 family of fatty acids because the liver can make other omega 3 fatty acids from it. linoleic acid (LA) (18:2n; ∆9,12); Is the "parent" fatty acid for the synthesis of other omega 6 fatty acids in the liver. It is found in the lipids of cell membrane. It is abundant in many vegetable oils, and sunflower oils. Arachidonic acid (20;4n;5,8,11,14) Repair and Growth of skeletal muscle tissue Abundant fatty acids in the brain Play a central role in inflammation * تغريد محمود ابراهيم مصطفى فدوى سعد محمد (أعادة) سهى هشام بدر عباس أسماء محمد حسن روزالين راوبين يعقوب فرج فاطمة سعد محمد أسراء محمد حافظ هاجر عبد الشفيع هدير السيد أحمد عال حازم علي حسن رحمه مسعد عبد اللطيف غنيم أسراء كامل السيد نهاد خالد عبد اللطيف السيد مصطفى السيد أحمد شفيق محمد هند أحمد أبراهيم نورهان اشرف السيد الشرنوبي خليفة سهيله نبيل حامد عبد القادر عبد الرحمن السيد علي محمود رامي عقيلة ASSIGNMENTS • Selected students are requested to prepare slides about one of the following topics (To be delivered before next lecture): • Lipids and disease • Healthy lipids • Unhealthy lipids • Atherosclerosis • Saturated Fatty acids • Unsaturated fatty acids • Triglyceridss Complete: * -----------,--------------------and------------------are essential fatty acids. * ----------------and --------------are saturated fatty acids. * All --------------and---------------are non essential amino acids. * ----------------------- is the parent compound of glycerophspholipids. * Lipids includes three main classes which are-----,--------and------- 1-Essential amino acids are synthesized in human body. 2-Saturated fatty acids have one or more double bonds. 3- Alpha linolenic acid is non-essential amino acid. 4- Palmitoleic acid is essential amino acid. Principles of Biochemistry, Donald J. Voet, Judith G. Voet, Charlotte W. pratt; Willey, 3rd ed.