2.03 Carbohydrates Flashcards
Monomers or building blocks for all other classes of carbohydrates
Monososacharide
General formula of carbohydrate
Cn(H2o)n
Consisting of at least 3 carbons, each with a hydroxyl group except for one with carbonyl carbon
Monosaccharide
Produced by joining two simple sugars by dehydration synthesis forming covalent bond
Disaccharide
Produced by joining many monosaccharides together by many dehydration synthesis reactions forming a polymer molecules
Polysaccharides
Used to measure blood glucose levels
Needs a few microliter of blood
Glucometer
Most important monosaccharide in the biological system
Main source of energy
Glucose
Very low glucose level
Hypoglycemia
Very high glucose level
Hyperglycemia
Two dimensional representation for showing the configuration of a stererocenter
Fischer projection
Named after English chemist Sir Walter Haworth
Ring is drawn flat and viewed through its edge with the anomeric carbon on the right and the oxygen atom to the rear
Haworth Projection
Cannot be hydrolyzed to a simpler compound
Monosaccharide
Only two trioses
Found in glycolysis as breakdown products from fructose-1,6-bisphosphate
D-glyceraldehyde
Dihydroxyacetone
With an aldehyde group at one end
Aldose
Keto group found at nonterminal carbons
Ketose
Two major forms have the same atomic composition but differ only in the position of the hydrogen and double bonds
Tautomer
Carbon atoms that carry 4 different substituents or entities
Chiral or asymmetric carbon
Molecules that have the same formula and the same structure, but have their atoms arranged in different ways in 3D space
Stereoisomers or isomers
Isomers that are mirror images of one another but are non-superimposable on one another
Enantiomers
Enantiomer designation
Right hand side
Dextrorotatory
D-isomers
Constituent of ribonucleic acid
D-ribose
Enantiomer designation
Left hand side
Levorototary
D-isomers
Constituent of deoxyribonucleic acid
D-deoxyribose
D-isomers
Milk
D-galactose
D-isomers
Major energy source
D-glucose
D-isomers
Intermediate in glycolysis
D-fructose
Isomers that are not mirror images of each other but with the same chemical composition
Diastereomers
Diastereomers that differ from each other in their configuration around one chiral c atom only
Epimers
Isomers that differ in configuration at the anomeric carbon
Anomers
Molecules with the same stereochemical configuration, but differing in 3-dimensional conformation
Conformational isomers
More stable conformation because of hydroxyl of carbon 1 and 2 are further removed and thus have less steric interference with the carbons 3,4 and 5
Chair conformation
How many stereoisomers does a 5-C aldose have?
8 (4 D-sugars and 4 L-sugars)
Pentose and hexose can cyclize as the ketone and aldehyde reacts with a distal OH forming either _______ or ________
Furanose
Pyrannose
Derivatives of carbohydrates
Reducing sugar Sugar alcohol Amino sugar Phosphorylation derivatives Glycosides
With free anomeric carbons
Undergoing redox reactions with the agents (peroxide, ferricyanide and some metals)
Reducing sugars
Lacks an aldehyde or ketone
Reducing the carbonyl group of a sugar
Sugar alcohol
D-mannitol
Sugar alcohol
Sorbitol, sweetener
Sugar alcohol
An amino group substitutes for a hydroxyl
Amino sugar
Glucosamine
Amino sugar
May be esterifying a phosphate group to one of the hydroxyls
Phosphorylated derivatives
Formed by elimination of water between the anomeric hydroxyl of a cyclic monosaccharide and the hydroxyl group f another compound
Glycosides
Ouabain
Amygdalin
Glycosides
Composed of two monosaccharides joined together by glycosidic bonds
Disaccharide
4 features that distinguish disaccharides from each other
Specific sugar monomer, stereoconfiguration
Carbons involved in the linkage/glycosidic bond
Order of the monomeric units
Anomeric configuration of the hydroxyl group in carbon 1 of each residue
Glucose + glucose
Alpha (1->4) glycosidic linkage
Maltose
Glucose + fructose
Alpha (1->2) glycosidic bond
Sucrose
Glucose + galactose
Beta (1->4) glycosidic bond
Lactose
Polysaccharides with 3-20 monomeric units
Oligosaccharides
2 types of glycosidic linkages in oligosaccharide a
O-linked oligosaccharide chains of glycoproteins
N-linked oligosaccharide chains of glycoproteins
Link to the protein via a glycosidic bond between a sugar residue and a serine or threonine OH
O-linked oligosaccharide chains
Tend to be complex and branched
N-acetylglucosamine linked via N of asparagine residue
N-linked oligosaccharide chains of glycoproteins
Biological significance of oligosaccharides
Cell recognition and interaction
Enzyme regulation
Blood group antigens
Composed of many monomeric units
Polysaccharides
Polysaccharides of 1 type
Homopolysaccharide
Polysaccharide of multiple types
Heteropolysaccharide
Polymerization requires energy, meaning it is an ______ process
Anabolic
Properties that distinguish the various polysaccharides
Composition of monomeric unit
Linkages between the monomeric unit
Ways in which branches from the chains occur
Component sugar of cellulose
Glucose
Component sugar of amylose
Glucose
Component sugar of glycogen
Glucose
Component sugar of amylopectin
Glucose
Component sugar of agar
Galactose
Linear branched glucose polymer with alpha (1->4) linkages
Amylose
End glucose with an anomeric C1 that is not involved I the glycosidic bond
Reducing end
Glucose polymer with mainly alpha (1->4) linkages and alpha (1->6) linkages for branching parts
Amylopectin
Glucose polymer with alpha (1->6) linkages and is highly branched
Glycogen
Polymer of glucose with alpha (1->4) linkages and beta (1->6) linkages
Cellulose
Lubricant shock absorbent
Water binding
Hyaluronic acid
D-glucoronic acid
N-acetyl-D-glucosamine
Hyaluronic acid
Calcium accumulation
Cartilage and bone formation
Chondroitin-4-sulfate
D-glucoronic acid
N-acetyl-D-galactosamine-4-O-sulfate
Chondroitin-4-sulfate
Anticoagulant
Heparin
D-glucoronic acid
L-iduronic acid
N-sulfo-D-glucosamine
Heparin
Antibody
Gamma-globulin
N-acetyl-hexosamine
D-mannose
D-galactose
Gamma-globulin
Blood group specifically
Blood group substances
D-glucosamine
D-galactosamine
L-fucose
D-galactose
Blood group substance
Linear polymers of repeating disaccharides
Monomeric unit tend to be modified with acidic groups, amino groups, sulfated
Glycosaminoglycan
Repeating disaccharide of glucoronate and N-acetyl-glucosamine
Hyaluronate
GAGs covalently linked to serine residues of specific core proteins
Class of complex macromolecules that contain ~95% carbohydrate
Proteoglycans
Carbohydrate chain in the proteoglycan is called
Glycosaminoglycan
6 classes of proteoglycan
chondroitin sulphate dermatan sulphate keratin sulphate heparin sulphate heparin hyaluronate
Soluble glycosaminoglycan found in granules of mast cells
Highly sulphated
Heparin
Inhibits clot formation by interacting with the protein antithrombin
Heparin
Lack polymers
Shock absorber
Cementing substances
Hyaluronate
Most abundant GAG
Formation of bone, cornea
Chondroitin sulfate
Contains higher acelylated glucosamine than heparin
Heparan sulfate
More sulfated than heparin sulfates
Heparin
Synovial fluid, vitreous humor, ECM of loose connective tissue
Hyaluronate
Cartilage, bone, heart valves, cornea
Chrondroitin sulfate
Basement membrane, components of cell surfaces
Heparan sulfate
Component of intracellular granules of mast cells lining the arteries of the lungs, liver and skin
Heparin
Skin, blood vessels, heart valves
Dermatan sulfate
Cornea, bone, cartilage aggregated with chondroitin sulfate
Keratan sulfate
Function of carbohydrates
Energy source Supporting structures Component of nucleic acids DNA, RNA Immune system Signal transduction
Fructose, glucose, mannose and galactose have the same chemical formula C6H12O6; hence, they are all _____ of each other
Isomer
The structures of glucose and galactose differ only in the position of the hydroxyl group (-OH) at carbon 4; hence they are _______
C-4 epimers
The structures of glucose and mannose differ only in the position of the hydroxyl group (-OH) at carbon 2; hence they are _______
C-2 epimers
Galactose and mannose differ in the position of -OH groups at two carbons (2 and 4); hence, they are
Isomers
99% of the monosaccharides are in ______, in which the aldehyde (or keto) group has reacted with an alcohol group on the same sugar, making the carbonyl carbon assymetric
ring/cyclic form
Cyclization creates an anomeric carbon, generating ____ of the sugar
alpha and beta configurations
alpha-D-glucopyranose and beta-D-glucopyranose are both glucose but are _____ (differ in the projection of OH groups)
Anomers
The alpha and beta configurations are not mirror images. They are referred to as ___
Diastereomers
Sugars that can react with chromogenic agents causing the reagent to be reduced and colored, with the aldehyde group of the acyclic sugar becoming oxidized
Reducing sugar
Bonds that link sugars
Glycosidic bonds
Name the linkage.
Lactose is synthesized by forming a glycosidic bond between carbon 1 of beta-galactose and carbon 4 of glucose.
Beta (1->4) glycosidic bond
If the group on the non-carbohydrate molecule to which the sugar is attached is an -NH2 group, the bond is called an _____
N-glycosidic link
If the group on the non-carbohydrate molecule to which the sugar is attached is hydroxyl group, the bond is called an _____
O-glycosidic link
All sugar-sugar glycosidic bonds are _____
O-type linkages
If a pair of sugars are mirror images (enantiomers), the two members of the pair are designated as _____
D- and L-sugars
Glucose, with four aymmetric carbon atoms, can form how many isomers?
16
Isomerism that is determined by its spatial relationship to the parent compound of the carbohydrates
D and L isomerism
Presence of asymmetric carbon atoms also confers ___ on the compound
Optical activity
In solution, glucose is often (dextrorotatory or levorotatory) and in the (furanose or pyranose)
Dextrorotatory
Pyranose
Fructose has the same molecular formula as glucose but differs in its structures. There is a potential keto group in the anomeric carbon while in glucose, there is a potential aldehyde group in the anomeric carbon. This is an example of ______
Aldose-ketose isomerism
Formed by condensation between the hydroxyl group of the anomeric carbon of a monosaccharide, and a second compound that may or may not be another monosaccharide
Example is ouabain
Glycoside
Complex carbohydrates containing amino sugars and uronic acids
Glycosaminoglycans
GAGs + protein molecule
Preteoglycan