BIOCHEM 2

Carbohydrates

Biomolecules that are chemically simpler than nucleic acids and proteins, containing carbon, hydrogen, and oxygen.

Monosaccharides

The smallest unit of sugars that cannot be further hydrolyzed, typically containing 3-6 carbon atoms.

Isomerism

The existence of different types of isomers in monosaccharides.

Fischer Projection

A way to illustrate the open-chain structure of monosaccharides.

Haworth Projection

A way to illustrate the cyclic structure of monosaccharides.

Disaccharides

Carbohydrates composed of two monosaccharide units.

Hydrolysis

The process of breaking down disaccharides into monosaccharides through the addition of water.

Polysaccharides

Carbohydrates made up of polymers or chains of monosaccharide units.

Glycogen

A polysaccharide that serves as a short-term energy reserve in organisms.

Saccharide

The term used to refer to sugar units in carbohydrates.

Aldoses

Monosaccharides that contain an aldehyde group at Carbon 1.

Ketoses

Monosaccharides that contain a ketone group at Carbon 2.1. Aldehyde:A functional group characterized by a carbon atom double-bonded to an oxygen atom and single-bonded to a hydrogen atom.

Aldose

A monosaccharide that contains an aldehyde functional group.

Ketone

A functional group characterized by a carbon atom double-bonded to an oxygen atom.

Ketose

A monosaccharide that contains a ketone functional group.

Aldohexose

A hexose sugar that contains an aldehyde functional group.

Ketohexose

A hexose sugar that contains a ketone functional group.

Fischer Projection

A 2-D representation of the open-chain conformation of a monosaccharide, where the carbonyl group is at or near the top and carbon atoms are counted from the top.

Isomers

Molecules that have the same molecular formula but different arrangement, connectivity, and orientation in space.

Constitutional Isomers

Isomers that have the same molecular formula but different functional groups and different order of bonding atoms.

Stereoisomers

Isomers that have the same molecular formula and functional group, but different orientation of atoms around the molecule.

Stereogenic Carbon

A saturated carbon with four different groups around it, capable of producing stereoisomers.

Enantiomers

Stereoisomers that are non-superimposable mirror images of each other.

D-Glucose

A monosaccharide with the molecular formula C6H12O6, an aldohexose, and a D-enantiomer.

L-Glucose

A monosaccharide with the molecular formula C6H12O6, an aldohexose, and an L-enantiomer.1. Enantiomers:Two molecules that are mirror images of each other and have interchanged H and OH groups in the stereogenic carbons.

Diastereomers

Stereoisomers that are not mirror images of each other.

Epimers

Special class of diastereomers that differ in the position of only one -OH group.

D-glucose

Glucose with the OH of its penultimate carbon at the right.

L-glucose

Glucose with the OH of its penultimate carbon at the left.

D-ribose

Ribose with the OH of its second carbon as the C2 epimer.

D-arabinose

Arabinose with the OH of its second carbon as the C2 epimer.

Glucopyranose

Cyclic form of glucose in a pyranose structure.

Fructofuranose

Cyclic form of fructose in a furanose structure.

Anomers

Isomers of monosaccharides that differ only in the configuration about the anomeric carbon.

a-anomer

Anomer with the -OH of the anomeric carbon in the opposite direction as the terminal -CH2OH.

β-anomer

Anomer with the -OH of the anomeric carbon in the similar direction as the terminal -CH2OH.

Haworth projection

Representation of the cyclic structure of monosaccharides as hexagonal rings lying perpendicular to the plane of the paper.1. Furanoses:Pentagonal rings that lie perpendicular to the plane of the paper in the representation of monosaccharides.

Acetal oxygen

Located on the upper corner of the pentagon in a furanose.

Anomeric carbon

The rightmost vertex of a furanose or pyranose structure, carbon 1 in aldopentose and carbon 2 in ketohexose.

Haworth Projection

A method of representing cyclic monosaccharides where the position of hydroxyl (-OH) groups is indicated.

D or L isomer

Determined by the direction of the terminal -CH2OH group in a Haworth projection. Upwards for D isomer and downwards for L isomer.

Fischer Projection

A method of representing monosaccharides in a linear form.

Anomer

Refers to the configuration of the -OH group on the anomeric carbon, which can be in opposite or similar direction as the terminal -CH2OH.

Nomenclature of Cyclic Monosaccharides

The naming convention for cyclic monosaccharides, which includes the type of anomer, type of enantiomer, name of monosaccharide, and type of ring.

Pyranose

A six-membered ring structure formed when a monosaccharide cyclizes.

Furanose

A five-membered ring structure formed when a monosaccharide cyclizes.

Aldohexose

A monosaccharide with six carbon atoms and an aldehyde functional group.

Ketohexose

A monosaccharide with six carbon atoms and a ketone functional group.

Aldopentose

A monosaccharide with five carbon atoms and an aldehyde functional group.

Furanose

A five-membered ring structure formed when a monosaccharide cyclizes.

Ketohexose

A monosaccharide with six carbon atoms and a ketone functional group.

Anomeric carbon

The carbon atom in a cyclic monosaccharide that becomes chiral due to the formation of a new stereocenter.

Reducing monosaccharides

Monosaccharides that can be oxidized by weak oxidizing agents, forming aldonic acids.1. Monosaccharides:Simple sugars that cannot be broken down further.

Reducing agents

Substances that can donate electrons and cause a reduction reaction.

Weak oxidizing agents

Substances that can accept electrons and cause an oxidation reaction.

Colored reduced product

The product formed after a reduction reaction, which has a distinct color.

Benedict's Reagent

A weak oxidizing agent used to test for reducing sugars, which forms a blue brick red precipitate.

Fehling's Reagent

A weak oxidizing agent used to test for reducing sugars, which forms a blue brick red precipitate.

Tollen's Reagent

A weak oxidizing agent used to test for reducing sugars, which forms a colorless silver mirror.

Nylander's Reagent

A weak oxidizing agent used to test for reducing sugars, which forms a colorless black precipitate.

Picric Acid test

A test using picric acid to detect the presence of reducing sugars, which forms picramic acid.

Reducing sugars

Carbohydrates that can reduce weak oxidizing agents.

Ketoses

Monosaccharides that do not have a reducing property due to the absence of an aldehyde group.

Aldoses

Monosaccharides that have a reducing property due to the presence of an aldehyde group.

Glucosuria

A condition where glucose is present in the urine, indicating a symptom of diabetes.

Glucose oxidase

An enzyme specific for glucose, used for the detection of glucose without false positives.

Uronic acids

Monosaccharides with a carboxylic acid group formed by enzymatic oxidation.

Alduronic acid

Uronic acid with a carboxyl group as its conjugate base.

Alduronate

The conjugate base of an alduronic acid.

Sugar alcohols (alditols)

Monosaccharides that have undergone reduction, converting their carbonyls into alcohols.

NaBH4

A reducing agent used to convert carbonyls into alcohols.

Palladium (Pd) or Platinum (Pt)

Transition metal catalysts used in the reduction of carbonyls to alcohols.

Sorbitol

A common alditol found in various fruits and used as a sweetening agent.

Xylitol

A component of sugar-free gum.

Mannitol

Used in the treatment of malignant brain tumors to lower the blood-brain barrier.

Amino sugars

Monosaccharides with an amino group replacing a hydroxyl group.

N-acetyl derivatives

Amino sugars with an acetyl group attached to the amino group.

Chitin

A polysaccharide found in the exoskeleton of arthropods and cell walls1. Disaccharides:Carbohydrates comprising 2 monosaccharide units linked together via a glycosidic bond.

Glycosidic bond

The bond formed when the -OH of the anomeric carbon of a monosaccharide reacts with any -OH of another monosaccharide.

Reducing end

The end of a disaccharide that possesses one free unsubstituted anomeric carbon atom.

Non-reducing end

The end of a disaccharide that is involved in the glycosidic bond (acetal carbon) and does not have a free anomeric carbon.

Configuration of glycosidic bonds

The designation of the type of anomer and the carbon numbers involved in the glycosidic bond, such as a(1->4) or B(1->2).1. Maltose:A disaccharide produced from starch by the action of amylase enzymes. It is a component of malt and is important in brewing beer.

Cellobiose

A disaccharide produced from the acidic hydrolysis of cellulose. It cannot be hydrolyzed in the human body.

Lactose

The principal carbohydrate in milk, made up of D-galactose and D-glucose. It can be hydrolyzed in the human body.

Sucrose

Known as table sugar, it is a heterodisaccharide made up of D-glucose and D-fructose. It is a non-reducing disaccharide and can be hydrolyzed by diluted acids.

Hydrolysis

The breakdown of a large molecule into simpler units in the presence of water.

Disaccharidases

Enzymes in the digestive system that hydrolyze disaccharides into monosaccharides.

Lactase

A disaccharidase that cleaves lactose into galactose and glucose.

Maltase

A disaccharidase that cleaves the glycosidic bond in maltose.

Sucrase-isomaltase complex

An enzyme with two functional subunits that cleaves the glycosidic bonds in sucrose and isomaltose.

Lactose intolerance

A digestive disorder caused by a deficiency of lactase, resulting in the inability to digest lactose. Symptoms include bloating, diarrhea, and dehydration.1. Causes:genetic defect, physiological decline by age, and injuries to mucosa lining in the intestine caused by drugs or malnutrition

Diagnosis

Oral lactose tolerance test and/or H2 gas measurement in breath

Treatment

a. Reduce consumption of milk or dairy products, while eating yogurts and cheeses, as well as green vegetables such as broccoli, to ensure adequate calcium intake b. Use lactase-treated product. C. Take lactase in pill form prior to eating

Sugar Substitutes

Substances that impart sweet taste but have no caloric values, such as saccharin, aspartame, and sucralose

Polysaccharides

Carbohydrate material in nature that consists of polymers of monosaccharides and/or their derivatives

Homopolysaccharide

A polysaccharide that contains only one kind of monosaccharide molecule

Heteropolysaccharide

A polysaccharide that contains more than one kind of monosaccharide molecule

Common monosaccharide derivatives in polysaccharides

Amino sugars (D-glucosamine and D-galactosamine) and simple sugar acids (glucuronic and iduronic acids)

Common Properties of Polysaccharides

Amorphous powder in appearance, does not impart sweet taste, can be hydrolyzed but do not undergo fermentation, all polysaccharides are non-reducing, limited solubility in water

Factors in Identifying Polysaccharides

Nature of their component monosaccharides, type of glycosidic bond, length of their chains, and amount of chain branching