Carbohydrate - wikipedia Carbohydrate This is the latest accepted revision, reviewed on 21 March 2018. Lactose is a disaccharide found in animal milk. It consists of a molecule of D - galactose and a molecule of D - glucose bonded by beta - 1 - 4 glycosidic linkage. It has a formula of C H O. A carbohydrate is a biomolecule consisting of carbon ( C ), hydrogen ( H ) and oxygen ( O ) atoms, usually with a hydrogen -- oxygen atom ratio of 2 : 1 ( as in water ) ; in other words, with the empirical formula C ( H O ) ( where m may be different from n ). This formula holds true for monosaccharides. Some exceptions exist ; for example, deoxyribose, a sugar component of DNA, has the empirical formula C H O. The carbohydrates are technically hydrates of carbon ; structurally it is more accurate to view them as aldoses and ketoses. The term is most common in biochemistry, where it is a synonym of ' saccharide ', a group that includes sugars, starch, and cellulose. The saccharides are divided into four chemical groups : monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Monosaccharides and disaccharides, the smallest ( lower molecular weight ) carbohydrates, are commonly referred to as sugars. The word saccharide comes from the Greek word σάκχαρον ( sákkharon ), meaning `` sugar ''. While the scientific nomenclature of carbohydrates is complex, the names of the monosaccharides and disaccharides very often end in the suffix - ose. For example, grape sugar is the monosaccharide glucose, cane sugar is the disaccharide sucrose, and milk sugar is the disaccharide lactose. Carbohydrates perform numerous roles in living organisms. Polysaccharides serve for the storage of energy ( e.g. starch and glycogen ) and as structural components ( e.g. cellulose in plants and chitin in arthropods ). The 5 - carbon monosaccharide ribose is an important component of coenzymes ( e.g. ATP, FAD and NAD ) and the backbone of the genetic molecule known as RNA. The related deoxyribose is a component of DNA. Saccharides and their derivatives include many other important biomolecules that play key roles in the immune system, fertilization, preventing pathogenesis, blood clotting, and development. Carbohydrates are found in a wide variety of foods. The important sources are cereals ( wheat, maize, rice ), potatoes, sugarcane, fruits, table sugar ( sucrose ), bread, milk, etc. Starch and sugar are the important carbohydrates in our diet. Starch is abundant in potatoes, maize, rice and other cereals. Sugar appears in our diet mainly as sucrose ( table sugar ), which is added to drinks and many prepared foods such as jam, biscuits and cakes, and glucose and fructose which occur naturally in many fruits and some vegetables. Glycogen is a carbohydrate found in the liver and muscles ( as animal source ). Cellulose in the cell wall of all plant tissue is a carbohydrate. It is important in our diet as fibre which helps to maintain a healthy digestive system. Contents 1 Terminology 2 Structure 3 Division 4 Monosaccharides 4.1 Classification of monosaccharides 4.2 Ring - straight chain isomerism 4.3 Use in living organisms 5 Disaccharides 6 Nutrition 6.1 Classification 6.2 Effects of dietary carbohydrate restriction 7 Metabolism 7.1 Catabolism 8 Carbohydrate chemistry 9 See also 10 References 11 Sources 12 External links Terminology In scientific literature, the term `` carbohydrate '' has many synonyms, like `` sugar '' ( in the broad sense ), `` saccharide '', `` ose '', `` glucide '', `` hydrate of carbon '' or `` polyhydroxy compounds with aldehyde or ketone ''. Some of these terms, specially `` carbohydrate '' and `` sugar '', are also used with other meanings. In food science and in many informal contexts, the term `` carbohydrate '' often means any food that is particularly rich in the complex carbohydrate starch ( such as cereals, bread and pasta ) or simple carbohydrates, such as sugar ( found in candy, jams, and desserts ). Often in lists of nutritional information, such as the USDA National Nutrient Database, the term `` carbohydrate '' ( or `` carbohydrate by difference '' ) is used for everything other than water, protein, fat, ash, and ethanol. This will include chemical compounds such as acetic or lactic acid, which are not normally considered carbohydrates. It also includes dietary fiber which is a carbohydrate but which does not contribute much in the way of food energy ( calories ), even though it is often included in the calculation of total food energy just as though it were a sugar. In the strict sense, `` sugar '' is applied for sweet, soluble carbohydrates, many of which are used in food. Structure Formerly the name `` carbohydrate '' was used in chemistry for any compound with the formula C ( H O ). Following this definition, some chemists considered formaldehyde ( CH O ) to be the simplest carbohydrate, while others claimed that title for glycolaldehyde. Today, the term is generally understood in the biochemistry sense, which excludes compounds with only one or two carbons and includes many biological carbohydrates which deviate from this formula. For example, while the above representative formulas would seem to capture the commonly known carbohydrates, ubiquitous and abundant carbohydrates often deviate from this. For example, carbohydrates often display chemical groups such as : N - acetyl ( e.g. chitin ), sulphate ( e.g. glycosaminoglycans ), carboxylic acid ( e.g. sialic acid ) and deoxy modifications ( e.g. fucose and sialic acid ). Natural saccharides are generally built of simple carbohydrates called monosaccharides with general formula ( CH O ) where n is three or more. A typical monosaccharide has the structure H -- ( CHOH ) ( C = O ) -- ( CHOH ) -- H, that is, an aldehyde or ketone with many hydroxyl groups added, usually one on each carbon atom that is not part of the aldehyde or ketone functional group. Examples of monosaccharides are glucose, fructose, and glyceraldehydes. However, some biological substances commonly called `` monosaccharides '' do not conform to this formula ( e.g. uronic acids and deoxy - sugars such as fucose ) and there are many chemicals that do conform to this formula but are not considered to be monosaccharides ( e.g. formaldehyde CH O and inositol ( CH O ) ). The open - chain form of a monosaccharide often coexists with a closed ring form where the aldehyde / ketone carbonyl group carbon ( C = O ) and hydroxyl group ( -- OH ) react forming a hemiacetal with a new C -- O -- C bridge. Monosaccharides can be linked together into what are called polysaccharides ( or oligosaccharides ) in a large variety of ways. Many carbohydrates contain one or more modified monosaccharide units that have had one or more groups replaced or removed. For example, deoxyribose, a component of DNA, is a modified version of ribose ; chitin is composed of repeating units of N - acetyl glucosamine, a nitrogen - containing form of glucose. Division Carbohydrates are polyhydroxy aldehydes, ketones, alcohols, acids, their simple derivatives and their polymers having linkages of the acetal type. They may be classified according to their degree of polymerization and may be divided initially into three principal groups, namely sugars, oligosaccharides and polysaccharides The major dietary carbohydrates Class ( DP * ) Subgroup Components Sugars ( 1 -- 2 ) Monosaccharides Glucose, galactose, fructose, xylose Disaccharides Sucrose, lactose, maltose, trehalose Polyols Sorbitol, mannitol Oligosaccharides ( 3 -- 9 ) Malto - oligosaccharides Maltodextrins Other oligosaccharides Raffinose, stachyose, fructo - oligosaccharides Polysaccharides ( > 9 ) Starch Amylose, amylopectin, modified starches Non-starch polysaccharides Cellulose, hemicellulose, pectins, hydrocolloids DP * = Degree of polymerization Monosaccharides Main article : Monosaccharide D - glucose is an aldohexose with the formula ( C H O ). The red atoms highlight the aldehyde group and the blue atoms highlight the asymmetric center furthest from the aldehyde ; because this - OH is on the right of the Fischer projection, this is a D sugar. Monosaccharides are the simplest carbohydrates in that they can not be hydrolyzed to smaller carbohydrates. They are aldehydes or ketones with two or more hydroxyl groups. The general chemical formula of an unmodified monosaccharide is ( C H O ), literally a `` carbon hydrate ''. Monosaccharides are important fuel molecules as well as building blocks for nucleic acids. The smallest monosaccharides, for which n = 3, are dihydroxyacetone and D - and L - glyceraldehydes. Classification of monosaccharides The α and β anomers of glucose. Note the position of the hydroxyl group ( red or green ) on the anomeric carbon relative to the CH OH group bound to carbon 5 : they either have identical absolute configurations ( R, R or S, S ) ( α ), or opposite absolute configurations ( R, S or S, R ) ( β ). Monosaccharides are classified according to three different characteristics : the placement of its carbonyl group, the number of carbon atoms it contains, and its chiral handedness. If the carbonyl group is an aldehyde, the monosaccharide is an aldose ; if the carbonyl group is a ketone, the monosaccharide is a ketose. Monosaccharides with three carbon atoms are called trioses, those with four are called tetroses, five are called pentoses, six are hexoses, and so on. These two systems of classification are often combined. For example, glucose is an aldohexose ( a six - carbon aldehyde ), ribose is an aldopentose ( a five - carbon aldehyde ), and fructose is a ketohexose ( a six - carbon ketone ). Each carbon atom bearing a hydroxyl group ( - OH ), with the exception of the first and last carbons, are asymmetric, making them stereo centers with two possible configurations each ( R or S ). Because of this asymmetry, a number of isomers may exist for any given monosaccharide formula. Using Le Bel - va n't Hoff rule, the aldohexose D - glucose, for example, has the formula ( C H O ), of which four of its six carbons atoms are stereogenic, making D - glucose one of 2 = 16 possible stereoisomers. In the case of glyceraldehydes, an aldotriose, there is one pair of possible stereoisomers, which are enantiomers and epimers. 1, 3 - dihydroxyacetone, the ketose corresponding to the aldose glyceraldehydes, is a symmetric molecule with no stereo centers. The assignment of D or L is made according to the orientation of the asymmetric carbon furthest from the carbonyl group : in a standard Fischer projection if the hydroxyl group is on the right the molecule is a D sugar, otherwise it is an L sugar. The `` D - '' and `` L - '' prefixes should not be confused with `` d - '' or `` l - '', which indicate the direction that the sugar rotates plane polarized light. This usage of `` d - '' and `` l - '' is no longer followed in carbohydrate chemistry. Ring - straight chain isomerism Glucose can exist in both a straight - chain and ring form. The aldehyde or ketone group of a straight - chain monosaccharide will react reversibly with a hydroxyl group on a different carbon atom to form a hemiacetal or hemiketal, forming a heterocyclic ring with an oxygen bridge between two carbon atoms. Rings with five and six atoms are called furanose and pyranose forms, respectively, and exist in equilibrium with the straight - chain form. During the conversion from straight - chain form to the cyclic form, the carbon atom containing the carbonyl oxygen, called the anomeric carbon, becomes a stereogenic center with two possible configurations : The oxygen atom may take a position either above or below the plane of the ring. The resulting possible pair of stereoisomers is called anomers. In the α anomer, the - OH substituent on the anomeric carbon rests on the opposite side ( trans ) of the ring from the CH OH side branch. The alternative form, in which the CH OH substituent and the anomeric hydroxyl are on the same side ( cis ) of the plane of the ring, is called the β anomer. Use in living organisms Monosaccharides are the major source of fuel for metabolism, being used both as an energy source ( glucose being the most important in nature ) and in biosynthesis. When monosaccharides are not immediately needed by many cells they are often converted to more space - efficient forms, often polysaccharides. In many animals, including humans, this storage form is glycogen, especially in liver and muscle cells. In plants, starch is used for the same purpose. The most abundant carbohydrate, cellulose, is a structural component of the cell wall of plants and many forms of algae. Ribose is a component of RNA. Deoxyribose is a component of DNA. Lyxose is a component of lyxoflavin found in the human heart. Ribulose and xylulose occur in the pentose phosphate pathway. Galactose, a component of milk sugar lactose, is found in galactolipids in plant cell membranes and in glycoproteins in many tissues. Mannose occurs in human metabolism, especially in the glycosylation of certain proteins. Fructose, or fruit sugar, is found in many plants and in humans, it is metabolized in the liver, absorbed directly into the intestines during digestion, and found in semen. Trehalose, a major sugar of insects, is rapidly hydrolyzed into two glucose molecules to support continuous flight. Disaccharides Sucrose, also known as table sugar, is a common disaccharide. It is composed of two monosaccharides : D - glucose ( left ) and D - fructose ( right ). Main article : Disaccharide Two joined monosaccharides are called a disaccharide and these are the simplest polysaccharides. Examples include sucrose and lactose. They are composed of two monosaccharide units bound together by a covalent bond known as a glycosidic linkage formed via a dehydration reaction, resulting in the loss of a hydrogen atom from one monosaccharide and a hydroxyl group from the other. The formula of unmodified disaccharides is C H O. Although there are numerous kinds of disaccharides, a handful of disaccharides are particularly notable. Sucrose, pictured to the right, is the most abundant disaccharide, and the main form in which carbohydrates are transported in plants. It is composed of one D - glucose molecule and one D - fructose molecule. The systematic name for sucrose, O - α - D - glucopyranosyl - ( 1 → 2 ) - D - fructofuranoside, indicates four things : Its monosaccharides : glucose and fructose Their ring types : glucose is a pyranose and fructose is a furanose How they are linked together : the oxygen on carbon number 1 ( C1 ) of α - D - glucose is linked to the C2 of D - fructose. The - oside suffix indicates that the anomeric carbon of both monosaccharides participates in the glycosidic bond. Lactose, a disaccharide composed of one D - galactose molecule and one D - glucose molecule, occurs naturally in mammalian milk. The systematic name for lactose is O - β - D - galactopyranosyl - ( 1 → 4 ) - D - glucopyranose. Other notable disaccharides include maltose ( two D - glucoses linked α - 1, 4 ) and cellulobiose ( two D - glucoses linked β - 1, 4 ). Disaccharides can be classified into two types : reducing and non-reducing disaccharides. If the functional group is present in bonding with another sugar unit, it is called a reducing disaccharide or biose. Nutrition This article may lend undue weight to certain ideas, incidents, or controversies. Please help to create a more neutral presentation, with details put in their proper context. Discuss and resolve this issue before removing this message. ( June 2015 ) Grain products : rich sources of carbohydrates Carbohydrate consumed in food yields 3.87 calories of energy per gram for simple sugars, and 3.57 to 4.12 calories per gram for complex carbohydrate in most other foods. Relatively high levels of carbohydrate are associated with processed foods or refined foods made from plants, including sweets, cookies and candy, table sugar, honey, soft drinks, breads and crackers, jams and fruit products, pastas and breakfast cereals. Lower amounts of carbohydrate are usually associated with unrefined foods, including beans, tubers, rice, and unrefined fruit. Animal - based foods generally have the lowest carbohydrate levels, although milk does contain a high proportion of lactose. Organisms typically can not metabolize all types of carbohydrate to yield energy. Glucose is a nearly universal and accessible source of energy. Many organisms also have the ability to metabolize other monosaccharides and disaccharides but glucose is often metabolized first. In Escherichia coli, for example, the lac operon will express enzymes for the digestion of lactose when it is present, but if both lactose and glucose are present the lac operon is repressed, resulting in the glucose being used first ( see : Diauxie ). Polysaccharides are also common sources of energy. Many organisms can easily break down starches into glucose ; most organisms, however, can not metabolize cellulose or other polysaccharides like chitin and arabinoxylans. These carbohydrate types can be metabolized by some bacteria and protists. Ruminants and termites, for example, use microorganisms to process cellulose. Even though these complex carbohydrates are not very digestible, they represent an important dietary element for humans, called dietary fiber. Fiber enhances digestion, among other benefits. Based on the effects on risk of heart disease and obesity in otherwise healthy middle - aged adults, the Institute of Medicine recommends that American and Canadian adults get between 45 -- 65 % of dietary energy from whole - grain carbohydrates. The Food and Agriculture Organization and World Health Organization jointly recommend that national dietary guidelines set a goal of 55 -- 75 % of total energy from carbohydrates, but only 10 % directly from sugars ( their term for simple carbohydrates ). Classification Nutritionists often refer to carbohydrates as either simple or complex. However, the exact distinction between these groups can be ambiguous. The term complex carbohydrate was first used in the U.S. Senate Select Committee on Nutrition and Human Needs publication Dietary Goals for the United States ( 1977 ) where it was intended to distinguish sugars from other carbohydrates ( which were perceived to be nutritionally superior ). However, the report put `` fruit, vegetables and whole - grains '' in the complex carbohydrate column, despite the fact that these may contain sugars as well as polysaccharides. This confusion persists as today some nutritionists use the term complex carbohydrate to refer to any sort of digestible saccharide present in a whole food, where fiber, vitamins and minerals are also found ( as opposed to processed carbohydrates, which provide energy but few other nutrients ). The standard usage, however, is to classify carbohydrates chemically : simple if they are sugars ( monosaccharides and disaccharides ) and complex if they are polysaccharides ( or oligosaccharides ). In any case, the simple vs. complex chemical distinction has little value for determining the nutritional quality of carbohydrates. Some simple carbohydrates ( e.g. fructose ) raise blood glucose slowly, while some complex carbohydrates ( starches ), especially if processed, raise blood sugar rapidly. The speed of digestion is determined by a variety of factors including which other nutrients are consumed with the carbohydrate, how the food is prepared, individual differences in metabolism, and the chemistry of the carbohydrate. The USDA 's Dietary Guidelines for Americans 2010 call for moderate - to high - carbohydrate consumption from a balanced diet that includes six one - ounce servings of grain foods each day, at least half from whole grain sources and the rest from enriched. The glycemic index ( GI ) and glycemic load concepts have been developed to characterize food behavior during human digestion. They rank carbohydrate - rich foods based on the rapidity and magnitude of their effect on blood glucose levels. Glycemic index is a measure of how quickly food glucose is absorbed, while glycemic load is a measure of the total absorbable glucose in foods. The insulin index is a similar, more recent classification method that ranks foods based on their effects on blood insulin levels, which are caused by glucose ( or starch ) and some amino acids in food. Effects of dietary carbohydrate restriction See also : Low - carbohydrate diet Carbohydrates are a common source of energy in living organisms ; however, no single carbohydrate is an essential nutrient in humans. Humans are able to obtain all of their energy requirement from protein and fats, though the potential for some negative health effects of extreme carbohydrate restriction remains, as the issue has not been studied extensively yet. However, in the case of dietary fiber -- indigestible carbohydrates which are not a source of energy -- inadequate intake can lead to significant increases in mortality. Following a diet consisting of very low amounts of daily carbohydrate for several days will usually result in higher levels of blood ketone bodies than an isocaloric diet with similar protein content. This relatively high level of ketone bodies is commonly known as ketosis and is very often confused with the potentially fatal condition often seen in type 1 diabetics known as diabetic ketoacidosis. Somebody suffering ketoacidosis will have much higher levels of blood ketone bodies along with high blood sugar, dehydration and electrolyte imbalance. Long - chain fatty acids can not cross the blood -- brain barrier, but the liver can break these down to produce ketones. However, the medium - chain fatty acids octanoic and heptanoic acids can cross the barrier and be used by the brain, which normally relies upon glucose for its energy. Gluconeogenesis allows humans to synthesize some glucose from specific amino acids : from the glycerol backbone in triglycerides and in some cases from fatty acids. Metabolism Main article : Carbohydrate metabolism Carbohydrate metabolism denotes the various biochemical processes responsible for the formation, breakdown and interconversion of carbohydrates in living organisms. The most important carbohydrate is glucose, a simple sugar ( monosaccharide ) that is metabolized by nearly all known organisms. Glucose and other carbohydrates are part of a wide variety of metabolic pathways across species : plants synthesize carbohydrates from carbon dioxide and water by photosynthesis storing the absorbed energy internally, often in the form of starch or lipids. Plant components are consumed by animals and fungi, and used as fuel for cellular respiration. Oxidation of one gram of carbohydrate yields approximately 4 kcal of energy, while the oxidation of one gram of lipids yields about 9 kcal. Energy obtained from metabolism ( e.g., oxidation of glucose ) is usually stored temporarily within cells in the form of ATP. Organisms capable of aerobic respiration metabolize glucose and oxygen to release energy with carbon dioxide and water as byproducts. Catabolism Catabolism is the metabolic reaction which cells undergo to extract energy. There are two major metabolic pathways of monosaccharide catabolism : glycolysis and the citric acid cycle. In glycolysis, oligo / polysaccharides are cleaved first to smaller monosaccharides by enzymes called glycoside hydrolases. The monosaccharide units can then enter into monosaccharide catabolism. In some cases, as with humans, not all carbohydrate types are usable as the digestive and metabolic enzymes necessary are not present. Carbohydrate chemistry Carbohydrate chemistry is a large and economically important branch of organic chemistry. Some of the main organic reactions that involve carbohydrates are : Carbohydrate acetalisation Cyanohydrin reaction Lobry de Bruyn -- van Ekenstein transformation Amadori rearrangement Nef reaction Wohl degradation Koenigs -- Knorr reaction Carbohydrate digestion See also Bioplastic Fermentation Glycobiology Glycoinformatics Glycolipid Glycome Glycomics Glycosyl Macromolecule No - carbohydrate diet Pentose phosphate pathway Photosynthesis Resistant starch Saccharic acid Carbohydrate NMR References Jump up ^ Western Kentucky University ( May 29, 2013 ). `` WKU BIO 113 Carbohydrates ''. wku.edu. Jump up ^ Solomon EP, Berg LR, Martin DW ( 2004 ). Biology. Cengage Learning. p. 52. ISBN 978 - 0534278281 -- via google.books.com. Jump up ^ National Institute of Standards and Technology ( 2011 ). `` Material Measurement Library D - erythro - Pentose, 2 - deoxy - ''. nist.gov. ^ Jump up to : Long Island University ( May 29, 2013 ). `` The Chemistry of Carbohydrates '' ( PDF ). brooklyn.liu.edu. Jump up ^ Purdue University ( May 29, 2013 ). `` Carbohydrates : The Monosaccharides ''. purdue.edu. Jump up ^ Flitsch SL, Ulijn RV ( January 2003 ). `` Sugars tied to the spot ''. Nature. 421 ( 6920 ) : 219 -- 20. Bibcode : 2003Natur. 421... 219F. doi : 10.1038 / 421219a. PMID 12529622. ^ Jump up to : Avenas P ( 2012 ). `` Etymology of main polysaccharide names ''. In Navard P. The European Polysaccharide Network of Excellence ( EPNOE ) ( PDF ). Wien : Springer - Verlag. Jump up ^ Maton A, Hopkins J, McLaughlin CW, Johnson S, Warner MQ, LaHart D, Wright JD ( 1993 ). Human Biology and Health. Englewood Cliffs, New Jersey : Prentice Hall. pp. 52 -- 59. ISBN 0 - 13 - 981176 - 1. Jump up ^ USDA National Nutrient Database, 2015, p. 14 Jump up ^ Fearon WF ( 1949 ). Introduction to Biochemistry ( 2nd ed. ). London : Heinemann. Jump up ^ USDA National Nutrient Database, 2015, p. 13 Jump up ^ Coulter JM, Barnes CR, Cowles HC ( 1930 ). A Textbook of Botany for Colleges and Universities. Jump up ^ Burtis CA, Ashwood ER, Tietz NW ( 2000 ). Tietz fundamentals of clinical chemistry. Jump up ^ Matthews CE, Van Holde KE, Ahern KG ( 1999 ). Biochemistry ( 3rd ed. ). Benjamin Cummings. ISBN 0 - 8053 - 3066 - 6. Jump up ^ `` Chapter 1 -- The role of carbohydrates in nutrition ''. Carbohydrates in human nutrition. FAO Food and Nutrition Paper - 66. Food and Agriculture Organization of the United Nations. Jump up ^ Bertozzi CR, Rabuka D. `` Structural Basis of Glycan Diversity ''. Essentials of Glycobiology ( 3rd ed. ). Cold Spring Harbor ( NY ) : Cold Spring Harbor Laboratory Press. ISBN 978 - 1 - 621821 - 32 - 8. Jump up ^ Campbell NA, Williamson B, Heyden RJ ( 2006 ). Biology : Exploring Life. Boston, Massachusetts : Pearson Prentice Hall. ISBN 0 - 13 - 250882 - 6. Jump up ^ Pigman W, Horton D ( 1972 ). `` Chapter 1 : Stereochemistry of the Monosaccharides ''. In Pigman and Horton. The Carbohydrates : Chemistry and Biochemistry Vol 1A ( 2nd ed. ). San Diego : Academic Press. pp. 1 -- 67. Jump up ^ Pigman W, Anet E ( 1972 ). `` Chapter 4 : Mutarotations and Actions of Acids and Bases ''. In Pigman and Horton. The Carbohydrates : Chemistry and Biochemistry Vol 1A ( 2nd ed. ). San Diego : Academic Press. pp. 165 -- 94. Jump up ^ `` lyxoflavin ''. Merriam - Webster. Jump up ^ `` Show Foods ''. usda.gov. Jump up ^ `` Calculation of the Energy Content of Foods -- Energy Conversion Factors ''. fao.org. Jump up ^ `` Carbohydrate reference list '' ( PDF ). www.diabetes.org.uk. Retrieved October 30, 2016. Jump up ^ Pichon L, Huneau JF, Fromentin G, Tomé D ( May 2006 ). `` A high - protein, high - fat, carbohydrate - free diet reduces energy intake, hepatic lipogenesis, and adiposity in rats ''. The Journal of Nutrition. 136 ( 5 ) : 1256 -- 60. doi : 10.1093 / jn / 136.5. 1256. PMID 16614413. Jump up ^ Tighe P, Duthie G, Vaughan N, Brittenden J, Simpson WG, Duthie S, Mutch W, Wahle K, Horgan G, Thies F ( October 2010 ). `` Effect of increased consumption of whole - grain foods on blood pressure and other cardiovascular risk markers in healthy middle - aged persons : a randomized controlled trial ''. The American Journal of Clinical Nutrition. 92 ( 4 ) : 733 -- 40. doi : 10.3945 / ajcn. 2010.29417. PMID 20685951. Jump up ^ Food and Nutrition Board ( 2002 / 2005 ). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids. Washington, D.C. : The National Academies Press. Page 769. ISBN 0 - 309 - 08537 - 3. Jump up ^ Joint WHO / FAO expert consultation ( 2003 ). ( 1 ) ( PDF ). Geneva : World Health Organization. pp. 55 -- 56. ISBN 92 - 4 - 120916 - X. Jump up ^ Joint WHO / FAO expert consultation ( 1998 ), Carbohydrates in human nutrition, chapter 1. ISBN 92 - 5 - 104114 - 8. ^ Jump up to : `` Carbohydrates ''. The Nutrition Source. Harvard School of Public Health. Retrieved April 3, 2013. Jump up ^ Jenkins DJ, Jenkins AL, Wolever TM, Thompson LH, Rao AV ( February 1986 ). `` Simple and complex carbohydrates ''. Nutrition Reviews. 44 ( 2 ) : 44 -- 9. doi : 10.1111 / j. 1753 - 4887.1986. tb07585. x. PMID 3703387. Jump up ^ DHHS and USDA, Dietary Guidelines for Americans 2010. ^ Jump up to : Westman EC ( May 2002 ). `` Is dietary carbohydrate essential for human nutrition ? ''. The American Journal of Clinical Nutrition. 75 ( 5 ) : 951 -- 3 ; author reply 953 -- 4. doi : 10.1093 / ajcn / 75.5. 951a. PMID 11976176. Jump up ^ Park Y, Subar AF, Hollenbeck A, Schatzkin A ( June 2011 ). `` Dietary fiber intake and mortality in the NIH - AARP diet and health study ''. Archives of Internal Medicine. 171 ( 12 ) : 1061 -- 8. doi : 10.1001 / archinternmed. 2011.18. PMC 3513325. PMID 21321288. Jump up ^ Johnston CS, Tjonn SL, Swan PD, White A, Hutchins H, Sears B ( 2006 ). `` Ketogenic low - carbohydrate diets have no metabolic advantage over nonketogenic low - carbohydrate diets ''. The American Journal of Clinical Nutrition. 83 ( 5 ) : 1055 -- 61. doi : 10.1093 / ajcn / 83.5. 1055. PMID 16685046. Jump up ^ Ebert D, Haller RG, Walton ME ( 2003 ). `` Energy contribution of octanoate to intact rat brain metabolism measured by 13C nuclear magnetic resonance spectroscopy ''. The Journal of Neuroscience. 23 ( 13 ) : 5928 -- 35. PMID 12843297. Jump up ^ Marin - Valencia I, Good LB, Ma Q, Malloy CR, Pascual JM ( February 2013 ). `` Heptanoate as a neural fuel : energetic and neurotransmitter precursors in normal and glucose transporter I - deficient ( G1D ) brain ''. Journal of Cerebral Blood Flow and Metabolism. 33 ( 2 ) : 175 -- 82. doi : 10.1038 / jcbfm. 2012.151. PMID 23072752. Jump up ^ Horn RS. `` Integration of Metabolism ''. medbio.info. Jump up ^ Mehta S ( 9 October 2013 ). `` Energetics of Cellular Respiration ( Glucose Metabolism ) ''. Biochemistry Notes, Notes. Sources `` Compolition of foods raw, processed, prepared '' ( PDF ). United States Department of Agriculture. September 2015. Retrieved October 30, 2016. External links Wikimedia Commons has media related to Carbohydrates. Wikiquote has quotations related to : Carbohydrate Carbohydrates, including interactive models and animations ( Requires MDL Chime ) IUPAC - IUBMB Joint Commission on Biochemical Nomenclature ( JCBN ) : Carbohydrate Nomenclature Carbohydrates detailed Carbohydrates and Glycosylation -- The Virtual Library of Biochemistry, Molecular Biology and Cell Biology Functional Glycomics Gateway, a collaboration between the Consortium for Functional Glycomics and Nature Publishing Group Metabolism, catabolism, anabolism General Metabolic pathway Metabolic network Primary nutritional groups Energy metabolism Aerobic respiration Glycolysis → Pyruvate decarboxylation → Citric acid cycle → Oxidative phosphorylation ( electron transport chain + ATP synthase ) Anaerobic respiration Electron acceptors are other than oxygen Fermentation Glycolysis → Substrate - level phosphorylation ABE Ethanol Lactic acid Specific paths Protein metabolism Protein synthesis Catabolism Carbohydrate metabolism ( carbohydrate catabolism and anabolism ) Human Glycolysis ⇄ Gluconeogenesis Glycogenolysis ⇄ Glycogenesis Pentose phosphate pathway Fructolysis Galactolysis Glycosylation N - linked O - linked Nonhuman Photosynthesis Anoxygenic photosynthesis Chemosynthesis Carbon fixation Xylose metabolism Radiotrophism Lipid metabolism ( lipolysis, lipogenesis ) Fatty acid metabolism Fatty acid degradation ( Beta oxidation ) Fatty acid synthesis Other Steroid metabolism Sphingolipid metabolism Eicosanoid metabolism Ketosis Reverse cholesterol transport Amino acid Amino acid synthesis Urea cycle Nucleotide metabolism Purine metabolism Nucleotide salvage Pyrimidine metabolism Other Metal metabolism Iron metabolism Ethanol metabolism Food chemistry Additives Carbohydrates Coloring Enzymes Essential fatty acids Flavors Fortification Lipids `` Minerals '' ( Chemical elements ) Proteins Vitamins Water Types of carbohydrates General Aldose Ketose Furanose Pyranose Geometry Anomer Cyclohexane conformation Mutarotation Monosaccharides Dioses Aldodiose Glycolaldehyde Trioses Aldotriose Glyceraldehyde Ketotriose Dihydroxyacetone Tetroses Aldotetroses Erythrose Threose Ketotetrose Erythrulose Pentoses Aldopentoses Arabinose Lyxose Ribose Xylose Ketopentoses Ribulose Xylulose Deoxy sugars Deoxyribose Hexoses Aldohexoses Allose Altrose Galactose Glucose Gulose Idose Mannose Talose Ketohexoses Fructose Psicose Sorbose Tagatose Deoxy sugars Fucose Fuculose Rhamnose Heptoses Ketoheptoses Mannoheptulose Sedoheptulose Above 7 Octoses Nonoses Neuraminic acid Multiple Disaccharides Cellobiose Isomaltose Isomaltulose Lactose Lactulose Maltose Sucrose Trehalose Turanose Trisaccharides Maltotriose Melezitose Raffinose Tetrasaccharides Stachyose Other oligosaccharides Acarbose Fructooligosaccharide ( FOS ) Galactooligosaccharide ( GOS ) Isomaltooligosaccharide ( IMO ) Maltodextrin Mannan - oligosaccharides ( MOS ) Polysaccharides Beta - glucan Oat beta - glucan Lentinan Sizofiran Zymosan Cellulose Chitin Chitosan Dextrin / Dextran Fructose / Fructan Inulin Galactose / Galactan Glucose / Glucan Glycogen Hemicellulose Levan beta 2 → 6 Lignin Mannan Pectin Starch Amylopectin Amylose Xanthan gum LCCN : sh85020080 GND : 4164517 - 0 NDL : 00572696 Retrieved from `` https://en.wikipedia.org/w/index.php?title=Carbohydrate&oldid=831721483 '' Categories : Carbohydrates Nutrition Hidden categories : Wikipedia articles needing page number citations from January 2018 Wikipedia pending changes protected pages Use mdy dates from September 2015 Articles needing POV - check from June 2015 Wikipedia articles with LCCN identifiers Wikipedia articles with GND identifiers Talk Contents About Wikipedia Wikiquote Afrikaans Alemannisch Aragonés অসমীয়া Asturianu Azərbaycanca تۆرکجه বাংলা Bân - lâm - gú Башҡортса Беларуская Беларуская ( тарашкевіца ) ‎ Български Bosanski Буряад Català Čeština ChiShona Cymraeg Dansk Deutsch ދިވެހިބަސް Eesti Ελληνικά Español Esperanto Estremeñu Euskara فارسی Fiji Hindi Français Frysk Gaeilge Gàidhlig Galego 한국어 Հայերեն हिन्दी Hrvatski Ido Ilokano Bahasa Indonesia Interlingua Íslenska Italiano עברית Basa Jawa ಕನ್ನಡ ქართული Қазақша Kiswahili Kreyòl ayisyen Kurdî Кыргызча ລາວ Latina Latviešu Lëtzebuergesch Lietuvių Lumbaart Magyar Македонски മലയാളം მარგალური Bahasa Melayu Монгол မြန်မာဘာသာ Nederlands नेपाली नेपाल भाषा 日本 語 Nordfriisk Norsk Norsk nynorsk Occitan ଓଡ଼ିଆ Oromoo Oʻzbekcha / ўзбекча ਪੰਜਾਬੀ پنجابی Polski Português Română Runa Simi Русиньскый Русский Scots Shqip Sicilianu සිංහල Simple English Slovenčina Slovenščina کوردی Српски / srpski Srpskohrvatski / српскохрватски Basa Sunda Suomi Svenska Tagalog தமிழ் Татарча / tatarça తెలుగు ไทย Тоҷикӣ Türkçe Тыва дыл Українська اردو Vahcuengh Vèneto Tiếng Việt Winaray 吴语 ייִדיש 粵語 Žemaitėška 中文 डोटेली 111 more Edit links This page was last edited on 21 March 2018, at 22 : 46. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: the chemical formula cho can be classified as
Answer: carbohydrate