Carbohydrates (from 'hydrates of carbon') or saccharides (Greek σάκχαρον meaning "sugar") are the most abundant of the four major classes of biomolecules, which also include proteins, lipids and nucleic acids. Hydrate is a term used in Inorganic chemistry and Organic chemistry to indicate that a substance contains Water. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly Sugar is a class of edible Crystalline substances mainly Sucrose, Lactose, and Fructose. A biomolecule is any organic Molecule that is produced by living Organisms including large Polymeric molecules such as Proteins Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Lipids are broadly defined as any fat- Soluble ( lipophilic) naturally-occurring Molecule, such as fats oils waxes cholesterol sterols fat-soluble A nucleic acid is a Macromolecule composed of chains of monomeric Nucleotides In Biochemistry these Molecules carry Genetic information They fill numerous roles in living things, such as the storage and transport of energy (starch, glycogen) and structural components (cellulose in plants, chitin in animals). In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός Starch, CAS # 9005-25-8 Chemical formula (C6H10O5n is a Polysaccharide Glycogen is a Polysaccharide of Glucose (Glc which functions as the secondary short term energy storage in Animal cells Cellulose is an Organic compound with the formula, a Polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4 Chitin ( C 8 H 13 O 5 N)n (ˈkaɪtən is a long-chain Polymer of a N-acetylglucosamine Additionally, carbohydrates and their derivatives play major roles in the working process of the immune system, fertilization, pathogenesis, blood clotting, and development. An immune system is a collection of mechanisms within an Organism that protects against Disease by identifying and killing Pathogens and Tumor For soil improvement see Fertilization (soil. The term pathogenesis means step by step development of a disease due to a series of changes in the structure and /or function of a cell/tissue/organ being caused by a microbial, chemical or physical Coagulation is a complex process by which Blood forms Clots It is an important part of Hemostasis (the cessation of blood loss from a damaged vessel whereby Developmental Biology is the official journal of the Society for Developmental Biology. [1]
Chemically, carbohydrates are simple organic compounds that are aldehydes or ketones with many hydroxyl groups added, usually one on each carbon atom that is not part of the aldehyde or ketone functional group. An organic compound is any member of a large class of Chemical compounds whose Molecules contain Carbon. An aldehyde is an organic compound containing a terminal Carbonyl group. A ketone (pronounced as key tone) is either the Functional group characterized by a Carbonyl group (O=C linked to two other Carbon atoms or Hydroxyl in Chemistry stands for a molecule consisting of an Oxygen atom and a Hydrogen atom connected by a Covalent bond. In Organic chemistry, functional groups are specific groups of Atoms within Molecules that are responsible for the characteristic Chemical reactions The basic carbohydrate units are called monosaccharides, such as glucose, galactose, and fructose. Monosaccharides (from Greek monos: single sacchar: sugar are the most basic unit of Carbohydrates They consist of one sugar and Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. Galactose (Gal (also called brain sugar) is a type of Sugar which is less sweet than Glucose. Fructose (also levulose or laevulose) is a simple reducing Sugar ( Monosaccharide) found in many foods and is one of the three The general stoichiometric formula of an unmodified monosaccharide is (C·H2O)n, where n is any number of three or greater; however, the use of this word does not follow this exact definition and many molecules with formulae that differ slightly from this are still called carbohydrates, and others that possess formulae agreeing with this general rule are not called carbohydrates (eg formaldehyde). Stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry is the Calculation of Quantitative (measurable A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes [2]
Monosaccharides can be linked together into polysaccharides in almost limitless ways. Polysaccharides are relatively complex Carbohydrates They are Polymers made up of many Monosaccharides joined together by Glycosidic bonds 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-acetylglucosamine, a nitrogen-containing form of glucose. Deoxyribose, also known as D-Deoxyribose and 2-deoxyribose, is an Aldopentose &mdash a Monosaccharide containing five Carbon Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known Ribose (ɹˈaɪbəʊs ɹˈaɪbəɹʊs primarily seen as D-ribose, is an Aldopentose — a Monosaccharide containing five Carbon Chitin ( C 8 H 13 O 5 N)n (ˈkaɪtən is a long-chain Polymer of a N-acetylglucosamine N-Acetylglucosamine ( N-Acetyl-D-Glucosamine, or GlcNAc, or NAG) is a Monosaccharide derivative of Glucose. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 The names of carbohydrates often end in the suffix -ose.
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Monosaccharides
Monosaccharides are the simplest carbohydrates in that they cannot be hydrolyzed to smaller carbohydrates. The general chemical formula of an unmodified monosaccharide is (C•H2O)n, where n is any number of three or greater. A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes
Classification of monosaccharides
The α and β anomers of glucose. Alpha (uppercase Α, lowercase α; Αλφα is the first letter of the Greek alphabet. Beta (uppercase Β, lowercase β, internal ϐ; Βήτα Vita is the second letter of the Greek alphabet. In Sugar Chemistry, an anomer is a special type of Epimer. It is a Stereoisomer ( Diastereomer, more exactly of a Saccharide Note the position of the anomeric carbon (red or green) relative to the CH2OH group bound to carbon 5: they are either on the opposite sides (α), or the same side (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. In Organic chemistry, a carbonyl group is a Functional group composed of a Carbon Atom double-bonded to an Oxygen Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 The term chiral (pronounced /ˈkaɪɹ(əl̩/ is used to describe an object that is non- superimposable on its mirror image If the carbonyl group is an aldehyde, the monosaccharide is an aldose; if the carbonyl group is a ketone, the monosaccharide is a ketose. An aldehyde is an organic compound containing a terminal Carbonyl group. An aldose is a Monosaccharide (a simple Sugar) containing one Aldehyde group per Molecule and having a Chemical formula of the A ketone (pronounced as key tone) is either the Functional group characterized by a Carbonyl group (O=C linked to two other Carbon atoms or A ketose is a Sugar containing one Ketone group per Molecule. Monosaccharides with three carbon atoms are called trioses, those with four are called tetroses, five are called pentoses, six are hexoses, and so on. A triose is a Monosaccharide containing three Carbon Atoms There are only two trioses an aldotriose ( Glyceraldehyde) and a A tetrose is a Monosaccharide with 4 Carbon atoms They either have an Aldehyde Functional group in position 1 ( aldotetroses) A pentose is a Monosaccharide with five Carbon Atoms They either have an Aldehyde Functional group in position 1 ( aldopentoses In Organic chemistry, a hexose is a Monosaccharide with six Carbon atoms having the Chemical formula C6H12O6 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). Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. An aldohexose is a Hexose with an Aldehyde group on one end The aldohexoses have four Chiral centres for Ribose (ɹˈaɪbəʊs ɹˈaɪbəɹʊs primarily seen as D-ribose, is an Aldopentose — a Monosaccharide containing five Carbon A pentose is a Monosaccharide with five Carbon Atoms They either have an Aldehyde Functional group in position 1 ( aldopentoses Fructose (also levulose or laevulose) is a simple reducing Sugar ( Monosaccharide) found in many foods and is one of the three A ketohexose is a Ketone -containing Hexose (a six-carbon Monosaccharide)
Each carbon atom bearing a hydroxyl group (-OH), with the exception of the first and last carbons, are asymmetric, making them stereocenters with two possible configurations each (R or S). Hydroxyl in Chemistry stands for a molecule consisting of an Oxygen atom and a Hydrogen atom connected by a Covalent bond. The term chiral (pronounced /ˈkaɪɹ(əl̩/ is used to describe an object that is non- superimposable on its mirror image A stereocenter, or stereogenic centre, is any Atom in a Molecule bearing groups such that an interchanging of any two groups leads to a Stereoisomer Because of this asymmetry, a number of isomers may exist for any given monosaccharide formula. This article is about the chemical concept For "isomerism" of atomic nuclei see Nuclear isomer. The aldohexose D-glucose, for example, has the formula (C·H2O)6, of which all but two of its six carbons atoms are stereogenic, making D-glucose one of 24 = 16 possible stereoisomers. Stereoisomers are isomeric molecules that have the same molecular formula and sequence of bonded atoms (constitution but which differ in the three dimensional orientations In the case of glyceraldehyde, an aldotriose, there is one pair of possible stereoisomers, which are enantiomers and epimers. Glyceraldehyde is a Triose Monosaccharide with Chemical formula C 3 H 6 O 3 In Chemistry, an enantiomer ( from the Greek ἐνάντιος opposite and μέρος part or portion is one of two Stereoisomers that are nonsuperimposable In Chemistry, epimers are Diastereomers that differ in configuration of only one stereogenic center 1,3-dihydroxyacetone, the ketose corresponding to the aldose glyceraldehye, is a symmetric molecule with no stereocenters). Dihydroxyacetone (also known as DHA) is a simple Carbohydrate that is primarily used as an ingredient in Sunless tanning products 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. Because D sugars are biologically far more common, the D is often omitted.
Conformation
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. Hemiacetals and hemiketals are compounds of the general formula R1R2C(OHOR3 where R3 is not a hydrogen Hemiacetals and hemiketals are compounds of the general formula R1R2C(OHOR3 where R3 is not a hydrogen Rings with five and six atoms are called furanose and pyranose forms, respectively, and exist in equilibrium with the straight-chain form. A furanose is a simple Sugar that contains a five-membered Furan -based ring structure and is a sub-terminal ketone which gives it reducing power Pyranose is a collective term for Carbohydrates which have a chemical structure that includes a six-membered ring consisting of five carbons and one oxygen
During the conversion from straight-chain form to cyclic form, the carbon atom containing the carbonyl oxygen, called the anomeric carbon, becomes a chiral center with two possible configurations: the oxygen atom may take a position either above or below the plane of the ring. In Sugar Chemistry, an anomer is a special type of Epimer. It is a Stereoisomer ( Diastereomer, more exactly of a Saccharide The resulting possible pair of stereoisomers are called anomers. In Sugar Chemistry, an anomer is a special type of Epimer. It is a Stereoisomer ( Diastereomer, more exactly of a Saccharide In the α anomer, the -OH substituent on the anomeric carbon rests on the opposite side (trans) of the ring from the CH2OH side branch. Trans-2-butenesvg|right|thumb|Trans-2-butene]] In Chemistry, cis-trans isomerism or geometric isomerism or configuration isomerism is a form of The alternative form, in which the CH2OH substituent and the anomeric hydroxyl are on the same side (cis) of the plane of the ring, is called the β anomer. Because the ring and straight-chain forms readily interconvert, both anomers exist in equilibrium. In a Chemical process, chemical equilibrium is the state in which the chemical activities or Concentrations of the reactants and products have no net change
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. Metabolism is the set of Chemical reactions that occur in living Organisms in order to maintain Life. Biosynthesis is a phenomenon wherein Chemical compounds are produced from simpler Reagents Biosynthesis unlike Chemosynthesis, takes place within living When monosaccharides are not needed by cells they are quickly converted into another form, such as polysaccharides. Polysaccharides are relatively complex Carbohydrates They are Polymers made up of many Monosaccharides joined together by Glycosidic bonds
Disaccharides
Two joined monosaccharides are called disaccharides and represent the simplest polysaccharides. A disaccharide is a Sugar (a Carbohydrate) composed of two Monosaccharides 'Disaccharide' is one of the four chemical groupings of carbohydrates ( A disaccharide is a Sugar (a Carbohydrate) composed of two Monosaccharides 'Disaccharide' is one of the four chemical groupings of carbohydrates ( Examples include sucrose and lactose. Solubility of Pure SucroseTemperature(Cg Lactose (also referred to as milk sugar) is a Sugar which is found most notably in Milk. 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. In Chemistry, a glycosidic bond is a certain type of Functional group that joins a Carbohydrate (sugar molecule to another which may be another carbohydrate In Chemistry, a dehydration reaction is usually defined as a chemical reaction that involves the loss of water from the reacting molecule Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Hydroxyl in Chemistry stands for a molecule consisting of an Oxygen atom and a Hydrogen atom connected by a Covalent bond. The formula of unmodified disaccharides is C12H22O11. A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes 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. Solubility of Pure SucroseTemperature(Cg Plants are living Organisms belonging to the kingdom Plantae. It is composed of one D-glucose molecule and one D-fructose molecule. Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. Fructose (also levulose or laevulose) is a simple reducing Sugar ( Monosaccharide) found in many foods and is one of the three 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. There are millions of possible objects that can be described in science too many to create Common names for every one Pyranose is a collective term for Carbohydrates which have a chemical structure that includes a six-membered ring consisting of five carbons and one oxygen A furanose is a simple Sugar that contains a five-membered Furan -based ring structure and is a sub-terminal ketone which gives it reducing power
- The -oside suffix indicates that the anomeric carbon of both monosaccharides participates in the glycosidic bond. In Sugar Chemistry, an anomer is a special type of Epimer. It is a Stereoisomer ( Diastereomer, more exactly of a Saccharide
Lactose, a disaccharide composed of one D-galactose molecule and one D-glucose molecule, occurs naturally in milk. Lactose (also referred to as milk sugar) is a Sugar which is found most notably in Milk. Galactose (Gal (also called brain sugar) is a type of Sugar which is less sweet than Glucose. Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. Milk is an opaque white liquid produced by the Mammary glands of female Mammals (including Monotremes. The systematic name for lactose is O-β-D-galactopyranosyl-(1→4)-D-glucopyranose. There are millions of possible objects that can be described in science too many to create Common names for every one Other notable disaccharides include maltose (two D-glucoses linked α-1,4) and cellobiose (two D-glucoses linked β-1,4). Maltose, or malt sugar is a Disaccharide formed from two units of Glucose joined with an α(1→4 linkage Cellobiose is a Disaccharide with the formula 2O The molecule is derived from the condensation of two Glucose molecules linked in a β(1→4 bond
Oligosaccharides and polysaccharides
Oligosaccharides and polysaccharides are composed of longer chains of monosaccharide units bound together by glycosidic bonds. An oligosaccharide is a Saccharide polymer containing a small number (typically three to ten of component sugars also known as Simple sugars. Polysaccharides are relatively complex Carbohydrates They are Polymers made up of many Monosaccharides joined together by Glycosidic bonds The distinction between the two is based upon the number of monosaccharide units present in the chain. Oligosaccharides typically contain between two and nine monosaccharide units, and polysaccharides contain greater than ten monosaccharide units. Definitions of how large a carbohydrate must be to fall into each category vary according to personal opinion. Examples of oligosaccharides include the disaccharides mentioned above, the trisaccharide raffinose and the tetrasaccharide stachyose. Raffinose is a Trisaccharide composed of Galactose, Fructose, and Glucose.
Oligosaccharides are found as a common form of protein posttranslational modification. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Posttranslational modification (PTM is the chemical modification of a Protein after its translation. Such posttranslational modifications include the Lewis and ABO oligosaccharides responsible for blood group incompatibilities, the alpha-Gal epitope responsible for hyperacute rejection in xenotransplanation, and O-GlcNAc modifications. A blood type (also called a blood group) is a classification of Blood based on the presence or absence of inherited Antigenic substances on the
Polysaccharides represent an important class of biological polymers. A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds Their function in living organisms is usually either structure or storage related. A function is part of an answer to a question about why some object or process occurred in a system that Evolved through a process of Selection. Starch is used as a storage polysaccharide in plants, being found in the form of both amylose and the branched amylopectin. Starch, CAS # 9005-25-8 Chemical formula (C6H10O5n is a Polysaccharide Amylose ( CAS # 9005-82-7 is a planar Polymer of Glucose linked mainly by α(1→4 bonds Amylopectin ( CAS # 9037-22-3 is a highly branched Polymer of Glucose found in plants In animals, the structurally similar but more densely branched glycogen is used instead. Glycogen is a Polysaccharide of Glucose (Glc which functions as the secondary short term energy storage in Animal cells Glycogen's properties allow it to be metabolized more quickly, which suits the active lives of locomotive animals.
Cellulose and chitin are examples of structural polysaccharides. Cellulose is an Organic compound with the formula, a Polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4 Chitin ( C 8 H 13 O 5 N)n (ˈkaɪtən is a long-chain Polymer of a N-acetylglucosamine Cellulose is used in the cell walls of plants and other organisms, and is claimed to be the most abundant organic molecule on earth. A cell wall is a tough flexible and sometimes fairly rigid layer surrounding a cell, located external to the Cell membrane, which provides the cell with structural [3] It has a variety of uses including in the paper and textile industry and as a feedstock for the production of rayon (in the viscose process), cellulose acetate, celluloid and nitrocellulose. Chitin has a similar structure to cellulose but has nitrogen containing side branches, increasing its strength. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 It is found in arthropod exoskeletons and in the cell walls of some fungi. Arthropods are Animals belonging to the Phylum Arthropoda (from Greek ἄρθρον arthron, " Joint " An exoskeleton is an external Skeleton that supports and protects an animal's body in contrast to the internal Endoskeleton of for example a Human. A fungus (ˈfʌŋgəs is a eukaryotic Organism that is a member of the kingdom Fungi (ˈfʌndʒaɪ It has a variety of uses, for example in surgical threads.
Other polysaccharides include callose or laminarin, xylan, mannan, fucoidan, and galactomannan. Callose is a plant polysaccharide It is comprised of glucose residues linked together through b-13-linkages and is termed a B-glucan Laminarin (also known as laminaran is a storage Glucan (a Polysaccharide of Glucose) of Brown algae. Xylan is a generic term used to describe a wide variety of highly complex Polysaccharides that are found in plant cell walls and some Algae. Mannan is a Plant Polysaccharide that is a Polymer of the Sugar Mannose. Galactomannans are Polysaccharides consisting of a Mannose backbone with Galactose side groups (more specifically a (1-4-linked beta-D-mannopyranose backbone
Nutrition
Carbohydrates require less water to digest than proteins or fats and are the most common source of energy. Water is a common Chemical substance that is essential for the survival of all known forms of Life. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water Proteins and fat are vital building components for body tissue and cells and are also a source of energy for the body. Tissue is a cellular organizational level intermediate between cells and a complete organism The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called
Carbohydrates are not essential nutrients: the body can obtain all its energy from protein and fats[4][5]. An essential nutrient is a Nutrient required for normal body functioning that cannot be synthesized by the body and must be obtained from a dietary source The brain cannot burn fat and needs glucose for energy, but the body can make this glucose from protein. Carbohydrates contain 3. 75 and proteins 4 kilocalories per gram, respectively, while fats contain 9 kilocalories and alcohol contains 7 kilocalories per gram. This article is about the unit of energy For its use in Nutrition and Food labelling regulations, see the article on Food energy.
Foods that are high in carbohydrates include breads, pastas, beans, potatoes, bran, rice and cereals. Bread is a Staple food prepared by Baking a Dough of Flour and Water. Pasta ( Italian for "dough" is a generic term for Italian variants of Noodles. Bean is a common name for large plant Seeds of several genera of the family Fabaceae (formerly Leguminosae used for human food or animal The potato is a Starchy Tuberous crop Vegetable from the perennial Solanum tuberosum of the Solanaceae Bran is the hard outer layer of Grain and consists of combined Aleurone and Pericarp. Rice is a Cereal foodstuff which forms an important part of the diet of many people worldwide and as such it is a staple food for many
Based on evidence for risk of heart disease and obesity, the Institute of Medicine recommends that American and Canadian adults get between 40-65% of dietary energy from carbohydrates. The Institute of Medicine (IOM is one of the United States National Academies, and is a not-for-profit non-governmental American organization chartered in 1970 as a part of the United Food energy is the amount of Energy in food that is available through Digestion. [6] 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% should be from Free sugars (their definition of simple carbohydrates). [7]
Classification
Dietitians and nutritionists commonly classify carbohydrates as simple (monosaccharides and disaccharides) or complex (oligosaccharides and polysaccharides). A dietitian (also 'dietician' though 'dietitian' is used consistently by professionals is an expert in Food and Nutrition. The term nutritionist is subject to several interpretations In many jurisdictions a nutritionist is a health specialist who devotes professional activity to food and Nutritional Monosaccharides (from Greek monos: single sacchar: sugar are the most basic unit of Carbohydrates They consist of one sugar and A disaccharide is a Sugar (a Carbohydrate) composed of two Monosaccharides 'Disaccharide' is one of the four chemical groupings of carbohydrates ( An oligosaccharide is a Saccharide polymer containing a small number (typically three to ten of component sugars also known as Simple sugars. Polysaccharides are relatively complex Carbohydrates They are Polymers made up of many Monosaccharides joined together by Glycosidic bonds The term complex carbohydrate was first used in the Senate Select Committee publication Dietary Goals for the United States (1977), where it denoted "fruit, vegetables and whole-grains". [8] Dietary guidelines generally recommend that complex carbohydrates and nutrient-rich simple carbohydrates such as fruit and dairy products make up the bulk of carbohydrate consumption. The term fruit has different meanings dependent on context and the term is not synonymous in Food preparation and Biology. Dairy products are generally defined as Foodstuffs produced from Milk. The USDA's Dietary Guidelines for Americans 2005 dispenses with the simple/complex distinction, instead recommending fiber-rich foods and whole grains. [9]
The glycemic index and glycemic load systems are popular alternative classification methods which rank carbohydrate-rich foods based on their effect on blood glucose levels. The Glycemic index (also glycaemic index) or GI is a measure of the effects of Carbohydrates on Blood glucose levels The glycemic load (GL is a ranking system for Carbohydrate content in food portions based on their Glycemic index (GI and the portion size Blood sugar, used in a physiological context is a misnomer and misleading The insulin index is a similar, more recent classification method which ranks foods based on their effects on blood insulin levels. The Insulin Index is a measure used to quantify the typical Insulin response to various foods Insulin is a Hormone with intensive effects on both metabolism and several other body systems (eg vascular compliance This system assumes that high glycemic index foods and low glycemic index foods can be mixed to make the intake of high glycemic foods more acceptable.
Metabolism
Catabolism
Catabolism is the metabolic reaction cells undergo in order to extract energy. Carbohydrate metabolism denotes the various biochemical processes responsible for the formation, breakdown and interconversion of Carbohydrates There are two major metabolic pathways of monosaccharide catabolism:
Oligo/polysaccharides are cleaved first to smaller monosaccharides by enzymes called Glycoside hydrolases. In Biochemistry, a metabolic pathway is a series of chemical reactions occurring within a cell. For the related metabolic process see Anabolism. Catabolism is the set of Metabolic pathways which break down molecules into See also Gluconeogenesis, which carries out a process wherein glucose is synthesized rather than catabolized The citric acid cycle, also known as the tricarboxylic acid cycle ( TCA cycle) or the Krebs cycle, (or rarely the Szent-Györgyi–Krebs cycle Glycoside hydrolases (also called glycosidases) catalyze the Hydrolysis of the Glycosidic linkage to generate two smaller Sugars They The monosaccharide units can then enter into monosaccharide catabolism.
Carbohydrate chemistry
Carbohydrates are reactants in many organic reactions. Organic reactions are Chemical reactions involving Organic compounds The basic Organic chemistry reaction types are Addition reactions Elimination For example:
- Carbohydrate acetalisation
- Cyanohydrin reaction
- Lobry-de Bruyn-van Ekenstein transformation
- Amadori rearrangement
- Nef reaction
- Wohl degradation
- Koenigs-Knorr reaction
See also
- Biochemistry
- Gluconeogenesis
- Glycolipid
- Glycoprotein
- Macromolecules
- Nutrition
- Pentose phosphate pathway
- Photosynthesis
- Sugar
References
- ^ Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. In Carbohydrate chemistry carbohydrate acetalisation is an Organic reaction and a very effective means of providing a Protecting group. A Cyanohydrin reaction is an organic chemical reaction by an Aldehyde or Ketone with a Cyanide Anion or a Nitrile to form The Lobry-de Bruyn-van Ekenstein transformation also known as the Lobry-de Bruyn-van-Alberda-van-Ekenstein transformation is a base catalyzed Aldose The Amadori rearrangement is an Organic reaction describing the acid or base catalyzed Isomerization or Rearrangement reaction of the N- The Nef reaction is an Organic reaction describing the acid Hydrolysis of a salt of a primary or secondary Nitroalkane ( 1) to an The Koenigs–Knorr reaction in Organic chemistry is the substitution reaction of a Glycosyl Halide with an Alcohol to give a Biochemistry is the study of the chemical processes in living Organisms It deals with the Structure and function of cellular components such as Gluconeogenesis (abreviated GNG) is a Metabolic pathway that results in the generation of Glucose from non- Carbohydrate carbon substrates such Glycolipids are Carbohydrate -attached Lipids. Their role is to provide Energy and also serve as markers for cellular recognition Not to be confused with Peptidoglycan. Glycoproteins are proteins that contain Oligosaccharide chains ( Glycans) covalently attached The term macromolecule by definition implies "large Molecule " Nutrition (also called nourishment or aliment) is the provision to cells and Organisms of the materials necessary (in the form of food to support The pentose phosphate pathway (also called Phosphogluconate Pathway or HexoseMonophosphate Shunt shunt is a process that serves to generate NADPH and the synthesis of pentose Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy. Sugar is a class of edible Crystalline substances mainly Sucrose, Lactose, and Fructose. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall, 52-59. ISBN 0-13-981176-1.
- ^ Matthews, C. E. ; K. E. Van Holde; K. G. Ahern (1999) Biochemistry. 3rd edition. Benjamin Cummings. ISBN 0-8053-3066-6
- ^ N. A. Campbell (1996) Biology (4th edition). Benjamin Cummings NY. p. 23 ISBN 0-8053-1957-3
- ^ Is dietary carbohydrate essential for human nutrition? - Westman 75 (5): 951 - American Journal of Clinical Nutrition
- ^ A High-Protein, High-Fat, Carbohydrate-Free Diet Reduces Energy Intake, Hepatic Lipogenesis, and Adiposity in Rats - Pichon et al. 136 (5): 1256 - Journal of Nutrition
- ^ Food and Nutrition Board (2002/2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: The National Academies Press. National Academies Press ( NAP was created by the United States National Academies, to publish the reports issued by the United States National Academy of Sciences Page 769. ISBN 0-309-08537-3
- ^ Joint WHO/FAO expert consultation (2003). Diet, Nutrition and the Prevention of Chronic Diseases (PDF). Geneva: World Health Organization. Pages 55-56. ISBN 92-4-120916-X
- ^ Joint WHO/FAO expert consultation (1998), Carbohydrates in human nutrition, chapter 1. ISBN 92-5-104114-8.
- ^ DHHS and USDA, Dietary Guidelines for Americans 2005, Chapter 7 Carbohydrates
External links
- 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 and Cell Biology
- Consortium for Functional Glycomics
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