Triglyceride - wikipedia Triglyceride Example of an unsaturated fat triglyceride ( C H O ). Left part : glycerol ; right part, from top to bottom : palmitic acid, oleic acid, alpha - linolenic acid. A triglyceride ( TG, triacylglycerol, TAG, or triacylglyceride ) is an ester derived from glycerol and three fatty acids ( from tri - and glyceride ). Triglycerides are the main constituents of body fat in humans and other animals, as well as vegetable fat. They are also present in the blood to enable the bidirectional transference of adipose fat and blood glucose from the liver, and are a major component of human skin oils. There are many different types of triglyceride, with the main division between saturated and unsaturated types. Saturated fats are `` saturated '' with hydrogen -- all available places where hydrogen atoms could be bonded to carbon atoms are occupied. These have a higher melting point and are more likely to be solid at room temperature. Unsaturated fats have double bonds between some of the carbon atoms, reducing the number of places where hydrogen atoms can bond to carbon atoms. These have a lower melting point and are more likely to be liquid at room temperature. Contents 1 Chemical structure 1.1 Homotriglycerides 1.2 Chirality 2 Metabolism 3 Role in disease 3.1 Guidelines 3.2 Reducing triglyceride levels 4 Industrial uses 5 Staining 6 Interactive pathway map 7 See also 8 References Chemical structure Triglycerides are chemically tri esters of fatty acids and glycerol. Triglycerides are formed by combining glycerol with three fatty acid molecules. Alcohols have a hydroxyl ( HO -- ) group. Organic acids have a carboxyl ( -- COOH ) group. Alcohols and organic acids join to form esters. The glycerol molecule has three hydroxyl ( HO -- ) groups. Each fatty acid has a carboxyl group ( -- COOH ). In triglycerides, the hydroxyl groups of the glycerol join the carboxyl groups of the fatty acid to form ester bonds : HOCH CH ( OH ) CH OH + RCO H + R ′ CO H + R '' CO H → RCO CH CH ( O CR ′ ) CH CO R '' + 3H O The three fatty acids ( RCO H, R ′ CO H, R '' CO H in the above equation ) are usually different, but many kinds of triglycerides are known. The chain lengths of the fatty acids in naturally occurring triglycerides vary, but most contain 16, 18, or 20 carbon atoms. Natural fatty acids found in plants and animals are typically composed of only even numbers of carbon atoms, reflecting the pathway for their biosynthesis from the two - carbon building - block acetyl CoA. Bacteria, however, possess the ability to synthesise odd - and branched - chain fatty acids. As a result, ruminant animal fat contains odd - numbered fatty acids, such as 15, due to the action of bacteria in the rumen. Many fatty acids are unsaturated, some are polyunsaturated ( e.g., those derived from linoleic acid ). Most natural fats contain a complex mixture of individual triglycerides. Because of this, they melt over a broad range of temperatures. Cocoa butter is unusual in that it is composed of only a few triglycerides, derived from palmitic, oleic, and stearic acids in the 1 -, 2 -, and 3 - positions of glycerol, respectively. Homotriglycerides The simplest triglycerides are those where the three fatty acids are identical. Their names indicate the fatty acid : stearin derived from stearic acid, palmitin derived from palmitic acid, etc. These compounds can be obtained in three crystalline forms ( polymorphs ) : α, β, and β ′, the three forms differing in their melting points. Chirality If the first and third chain R and R '' are different, then the central carbon atom is a chiral centre, and as a result the triglyceride is chiral. Metabolism See also : Fatty acid metabolism The pancreatic lipase acts at the ester bond, hydrolyzing the bond and `` releasing '' the fatty acid. In triglyceride form, lipids can not be absorbed by the duodenum. Fatty acids, monoglycerides ( one glycerol, one fatty acid ), and some diglycerides are absorbed by the duodenum, once the triglycerides have been broken down. In the intestine, following the secretion of lipases and bile, triglycerides are split into monoacylglycerol and free fatty acids in a process called lipolysis. They are subsequently moved to absorptive enterocyte cells lining the intestines. The triglycerides are rebuilt in the enterocytes from their fragments and packaged together with cholesterol and proteins to form chylomicrons. These are excreted from the cells and collected by the lymph system and transported to the large vessels near the heart before being mixed into the blood. Various tissues can capture the chylomicrons, releasing the triglycerides to be used as a source of energy. Liver cells can synthesize and store triglycerides. When the body requires fatty acids as an energy source, the hormone glucagon signals the breakdown of the triglycerides by hormone - sensitive lipase to release free fatty acids. As the brain can not utilize fatty acids as an energy source ( unless converted to a ketone ), the glycerol component of triglycerides can be converted into glucose, via gluconeogenesis by conversion into dihydroxyacetone phosphate and then into glyceraldehyde 3 - phosphate, for brain fuel when it is broken down. Fat cells may also be broken down for that reason if the brain 's needs ever outweigh the body 's. Triglycerides can not pass through cell membranes freely. Special enzymes on the walls of blood vessels called lipoprotein lipases must break down triglycerides into free fatty acids and glycerol. Fatty acids can then be taken up by cells via the fatty acid transporter ( FAT ). Triglycerides, as major components of very - low - density lipoprotein ( VLDL ) and chylomicrons, play an important role in metabolism as energy sources and transporters of dietary fat. They contain more than twice as much energy ( approximately 9 kcal / g or 38 kJ / g ) as carbohydrates ( approximately 4 kcal / g or 17 kJ / g ). Role in disease Main article : Hypertriglyceridemia In the human body, high levels of triglycerides in the bloodstream have been linked to atherosclerosis and, by extension, the risk of heart disease and stroke. However, the relative negative impact of raised levels of triglycerides compared to that of LDL : HDL ratios is as yet unknown. The risk can be partly accounted for by a strong inverse relationship between triglyceride level and HDL - cholesterol level. But the risk is also due to high triglyceride levels increasing the quantity of small, dense LDL particles. Guidelines Reference ranges for blood tests, showing usual ranges for triglycerides ( increasing with age ) in orange at right. The National Cholesterol Education Program has set guidelines for triglyceride levels : Level Interpretation ( mg / dL ) ( mmol / L ) < 150 < 1.70 Normal range -- low risk 150 -- 199 1.70 -- 2.25 Slightly above normal 200 -- 499 2.26 -- 5.65 Some risk 500 or higher > 5.65 Very high -- high risk These levels are tested after fasting 8 to 12 hours. Triglyceride levels remain temporarily higher for a period after eating. The American Heart Association recommends an optimal triglyceride level of 100 mg / dL ( 1.1 mmol / L ) or lower to improve heart health. Reducing triglyceride levels Weight loss and dietary modification are effective first - line lifestyle modification treatments for hypertriglyceridemia. For people with mildly or moderately high levels of triglycerides lifestyle changes including weight loss, moderate exercise and dietary modification are recommended. This may include restriction of carbohydrates ( specifically fructose ) and fat in the diet and the consumption of omega - 3 fatty acids from algae, nuts, and seeds. Medications are recommended in those with high levels of triglycerides that are not corrected with the aforementioned lifestyle modifications, with fibrates being recommended first. Epanova ( omega - 3 - carboxylic acids ) is another prescription drug used to treat very high levels of blood triglycerides. The decision to treat hypertriglyceridemia with medication depends on the levels and on the presence of other risk factors for cardiovascular disease. Very high levels that would increase the risk of pancreatitis is treated with a drug from the fibrate class. Niacin and omega - 3 fatty acids as well as drugs from the statin class may be used in conjunction, with statins being the main medication for moderate hypertriglyceridemia when reduction of cardiovascular risk is required. Industrial uses Linseed oil and related oils are important components of useful products used in oil paints and related coatings. Linseed oil is rich in di - and tri-unsaturated fatty acid components, which tend to harden in the presence of oxygen. This heat - producing hardening process is peculiar to these so - called drying oils. It is caused by a polymerization process that begins with oxygen molecules attacking the carbon backbone. Triglycerides are also split into their components via transesterification during the manufacture of biodiesel. The resulting fatty acid esters can be used as fuel in diesel engines. The glycerin has many uses, such as in the manufacture of food and in the production of pharmaceuticals. Staining Staining for fatty acids, triglycerides, lipoproteins, and other lipids is done through the use of lysochromes ( fat - soluble dyes ). These dyes can allow the qualification of a certain fat of interest by staining the material a specific color. Some examples : Sudan IV, Oil Red O, and Sudan Black B. Interactive pathway map Click on genes, proteins and metabolites below to link to respective articles. ( ( File : ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( ) ) px alt = Statin Pathway edit ) ) Statin Pathway edit Jump up ^ The interactive pathway map can be edited at WikiPathways : `` Statin_Pathway_WP430 ''. See also AIM - HIGH trial Diglyceride acyltransferase, enzyme responsible for triglyceride biosynthesis Medium - chain triglycerides Lipid profile Lipids Vertical auto profile References Jump up ^ `` Nomenclature of Lipids ''. IUPAC - IUB Commission on Biochemical Nomenclature ( CBN ). Retrieved 2007 - 03 - 08. Jump up ^ Nelson, D.L. ; Cox, M.M. ( 2000 ). Lehninger, Principles of Biochemistry ( 3rd ed. ). New York : Worth Publishing. ISBN 1 - 57259 - 153 - 6. Jump up ^ Lampe, M.A. ; Burlingame, A.L. ; Whitney, J. ; Williams, M.L. ; Brown, B.E. ; Roitman, E. ; Elias, M. ( 1983 ). `` Human stratum corneum lipids : characterization and regional variations ''. J. Lipid Res. 24 ( 2 ) : 120 -- 130. PMID 6833889. ^ Jump up to : Alfred Thomas ( 2002 ). `` Fats and Fatty Oils ''. Ullmann 's Encyclopedia of Industrial Chemistry. Ullmann 's Encyclopedia of Industrial Chemistry. Weinheim : Wiley - VCH. doi : 10.1002 / 14356007. a10_173. ISBN 3527306730. Jump up ^ Charbonnet, G.H. ; Singleton, W.S. ( 1947 ). `` Thermal properties of fats and oils ''. J. Am. Oil Chem. Soc. 24 ( 5 ) : 140. doi : 10.1007 / BF02643296. Jump up ^ C.M. Lok, J.P. Ward, D.A. van Dorp ( 1976 ). `` The synthesis of Chiral Glycerides starting from D - and L - serine '', Chemistry and Physics of Lipids, 16 ( 2 ) : 115 -- 122. Jump up ^ White, H., & Venkatesh, B. ( 2011 ). Clinical review : ketones and brain injury. Critical Care, 15 ( 2 ), 219 - 229. ^ Jump up to : Drummond, K.E. ; Brefere, L.M. ( 2014 ). Nutrition for Foodservice and Culinary Professionals ( 8th ed. ). John Wiley & Sons. ISBN 978 - 0 - 470 - 05242 - 6. Jump up ^ `` Boston scientists say triglycerides play key role in heart health ''. The Boston Globe. Retrieved 2014 - 06 - 18. Jump up ^ Ivanova EA, Myasoedova VA, Melnichenko AA, Grechko AV, Orekhov AN ( 2017 ). `` Small Dense Low - Density Lipoprotein as Biomarker for Atherosclerotic Diseases ''. Oxidative Medicine and Cellular Longevity. 2017 : 1273042. doi : 10.1155 / 2017 / 1273042. PMC 5441126. PMID 28572872. Jump up ^ `` Triglycerides ''. MedlinePlus. Archived from the original on 26 October 2012. Retrieved 2015 - 04 - 23. Jump up ^ Crawford, H., Micheal. Current Diagnosis & Treatment Cardiology. 3rd ed. McGraw - Hill Medical, 2009. p19 Jump up ^ `` What 's considered normal ? ''. Triglycerides : Why do they matter ?. Mayo Clinic. 28 September 2012. ^ Jump up to : Nordestgaard, BG ; Varbo, A ( August 2014 ). `` Triglycerides and cardiovascular disease ''. The Lancet. 384 ( 9943 ) : 626 -- 35. doi : 10.1016 / S0140 - 6736 ( 14 ) 61177 - 6. PMID 25131982. Jump up ^ GILL, Jason ; Sara HERD ; Natassa TSETSONIS ; Adrianne HARDMAN ( Feb 2002 ). `` Are the reductions in triacylglycerol and insulin levels after exercise related ? ''. Clinical Science. 102 ( 2 ) : 223 -- 231. doi : 10.1042 / cs20010204. PMID 11834142. Retrieved 2 March 2013. ^ Jump up to : Crawford, H., Micheal. Current Diagnosis & Treatment Cardiology. 3rd ed. McGraw - Hill Medical, 2009. p21 ^ Jump up to : Berglund L, Brunzell JD, Goldberg AC, et al. ( September 2012 ). `` Evaluation and treatment of hypertriglyceridemia : an endocrine society clinical practice guideline ''. J. Clin. Endocrinol. Metab. 97 ( 9 ) : 2969 -- 89. doi : 10.1210 / jc. 2011 - 3213. PMC 3431581. PMID 22962670. Jump up ^ Davidson, Michael H. ( 28 January 2008 ). `` Pharmacological Therapy for Cardiovascular Disease ''. In Davidson, Michael H. ; Toth, Peter P. ; Maki, Kevin C. Therapeutic Lipidology. Contemporary Cardiology. Cannon, Christopher P. ; Armani, Annemarie M. Totowa, New Jersey : Humana Press, Inc. pp. 141 -- 142. ISBN 978 - 1 - 58829 - 551 - 4. Jump up ^ Abourbih S, Filion KB, Joseph L, Schiffrin EL, Rinfret S, Poirier P, Pilote L, Genest J, Eisenberg MJ ( 2009 ). `` Effect of fibrates on lipid profiles and cardiovascular outcomes : a systematic review ''. Am J Med. 122 ( 10 ) : 962. e1 -- 962. e8. doi : 10.1016 / j. amjmed. 2009.03. 030. PMID 19698935. Jump up ^ Jun M, Foote C, Lv J, et al. ( 2010 ). `` Effects of fibrates on cardiovascular outcomes : a systematic review and meta - analysis ''. Lancet. 375 ( 9729 ) : 1875&ndash, 1884. doi : 10.1016 / S0140 - 6736 ( 10 ) 60656 - 3. Jump up ^ Blair HA, Dhillon S. Omega - 3 carboxylic acids ( Epanova ) : a review of its use in patients with severe hypertriglyceridemia. Am J Cardiovasc Drugs. 2014 Oct ; 14 ( 5 ) : 393 - 400. PMID 25234378 Types of lipids General Saturation : Saturated fat Unsaturated fat Monounsaturated fat Polyunsaturated fat Essential fatty acid Other : Fat Oil Geometry Trans fat Omega - 3 fatty acid Omega - 6 fatty acid Omega - 9 fatty acid Eicosanoids Arachidonic acid Prostaglandins Prostacyclin Thromboxane Leukotrienes Fatty acids Caprylic acid Capric acid Lauric acid Myristic acid Palmitic acid Stearic acid Arachidic acid Behenic acid Lignoceric acid Glycerides Monoglyceride Diglyceride Triglyceride Triheptanoin Trimyristin Tripalmitin Tristearin Trilinolein Triolein Phospholipids Phosphatidylserine Phosphatidylinositol Phosphatidyl ethanolamine Cardiolipin Dipalmitoylphosphatidylcholine Sphingolipids Ceramide Steroids Cholesterol Corticosteroids Sex steroids Secosteroids GND : 4127027 - 7 LCCN : sh85137515 Retrieved from `` https://en.wikipedia.org/w/index.php?title=Triglyceride&oldid=864730371 '' Categories : Triglycerides Lipid disorders Hidden categories : Wikipedia articles with GND identifiers Wikipedia articles with LCCN identifiers Talk Contents About Wikipedia Azərbaycanca Bân - lâm - gú Беларуская Беларуская ( тарашкевіца ) ‎ Català Čeština Dansk Deutsch Ελληνικά Español Esperanto Euskara فارسی Français Gaeilge Galego 한국어 Հայերեն हिन्दी Hrvatski Bahasa Indonesia Íslenska Italiano עברית Қазақша Кыргызча Lietuvių Magyar Македонски Bahasa Melayu Nederlands 日本 語 Norsk Oʻzbekcha / ўзбекча Polski Português Română Русский Scots Simple English Slovenčina Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska Tagalog தமிழ் Татарча / tatarça ไทย Тоҷикӣ Türkçe Тыва дыл Українська Tiếng Việt 中文 47 more Edit links This page was last edited on 19 October 2018, at 02 : 43 ( UTC ). 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Question: cells that have the ability to store triglycerides are
Answer: Liver cells