Carbohydrates: General Aspects and Classification

Comprehensive vocabulary flashcards covering the definition, general structure, classification, and examples of monosaccharides, oligosaccharides, and polysaccharides.

Carbohydrates

Aldehyde or ketone compounds with multiple hydroxyl groups, or compounds that yield them on hydrolysis, having at least three carbon atoms with potentially active carbonyl groups.

Monosaccharides

Simple sugars consisting of a single polyhydroxy aldehyde or ketose unit that cannot be further hydrolyzed to simpler carbohydrates, generally following the empirical formula $(CH_2O)_n$ where $n = 3$ or larger.

Carbonyl groups

The collective name given to the aldehyde and ketone functional groups present in monosaccharides.

Aldose

A monosaccharide containing an aldehyde group, which is always located at an end of the carbon chain.

Ketose

A monosaccharide containing a ketone group, which never occurs at an end of the molecule.

Trioses

Monosaccharides containing three carbon atoms; examples include the aldose glyceraldehyde (glycerose) and the ketose dihydroxyacetone.

Tetroses

Monosaccharides containing four carbon atoms; examples include the aldose erythrose and the ketose erythrulose.

Pentoses

Monosaccharides containing five carbon atoms; examples include the aldose ribose and the ketose ribulose.

Hexoses

Monosaccharides containing six carbon atoms; examples include the aldohexose glucose and the ketohexose fructose.

Heptoses

Monosaccharides containing seven carbon atoms; examples include the aldose glucoheptose and the ketose sedoheptulose.

Oligosaccharides

Short-chain condensation products of two to ten (or twenty according to some authors) monosaccharide units covalently joined by O-glycosidic linkages.

Maltose

A physiologically important disaccharide consisting of two glucose units.

Sucrose (Saccharose)

A physiologically important disaccharide composed of one unit of glucose and one unit of fructose.

Lactose

A physiologically important disaccharide composed of one unit of glucose and one unit of galactose.

Isomaltose

An oligosaccharide consisting of a glucose dimer linked by a 1-6 glycosidic bond.

Trehalose

An oligosaccharide consisting of a glucose dimer linked by a $1 \rightarrow 1$ glycosidic bond.

Polysaccharides

Sugar polymers containing a large number of monosaccharide units (more than ten or twenty) that serve as fuel stores and structural cellular elements.

Homopolysaccharides

Polysaccharides that on hydrolysis yield only one type of monomer; includes starch, glycogen, cellulose, dextrans, and chitin.

Chitin

A homopolysaccharide composed of a polymer of $\beta(1-4)$-N-acetylated glucosamine.

Heteropolysaccharides

Polysaccharides containing two or more types of monosaccharide derivatives along with certain other molecules.

Glycos-amino-glycans (GAGs)

Also called copolysaccharides; a subgroup of heteropolysaccharides containing carbohydrate parts and acid groups, such as hyaluronic acid, chondroitin sulfates, and heparin.

Glyco-conjugates

A subgroup of heteropolysaccharide complexes that include proteoglycans, glycoproteins, and glycolipids.