Carbohydrates Structure and Function

Vocabulary practice flashcards covering carbohydrate definitions, classifications, isomerism, and structural forms.

Carbohydrate

Aldehyde or ketone derivatives of polyhydric alcohols, or larger molecules that can be hydrolyzed into polyhydroxy aldehydes or ketones.

Monosaccharide

The simplest single sugar unit carbohydrate that cannot be hydrolyzed into simpler carbohydrate units.

Triose

A monosaccharide containing 3 carbon atoms, such as glycerose or dihydroxyacetone.

Tetrose

A monosaccharide containing 4 carbon atoms, such as erythrose or erythrulose.

Pentose

A monosaccharide containing 5 carbon atoms, such as ribose or ribulose.

Hexose

A monosaccharide containing 6 carbon atoms, such as glucose or fructose.

Aldose

A classification of monosaccharide that contains an aldehyde functional group, including glycerose, erythrose, ribose, and glucose.

Ketose

A classification of monosaccharide that contains a ketone functional group, including dihydroxyacetone, erythrulose, ribulose, and fructose.

Disaccharide

A carbohydrate sugar composed of two monosaccharides linked by an $\alpha$ or $\beta$ glycosidic bond with the loss of a water molecule.

Oligosaccharide

A carbohydrate that yields 3 to 10 monosaccharide units upon hydrolysis, such as maltotriose.

Polysaccharide

A carbohydrate that yields more than 10 monosaccharide molecules upon hydrolysis, categorized into homopolysaccharides and heteropolysaccharides.

Asymmetric Carbon Atom

A carbon atom attached to four different atoms or groups, which enables the formation of carbohydrate isomers.

Enantiomers

Stereoisomers that are non-superimposable mirror images of each other, designated D- or L- based on whether the reference hydroxyl group is on the right or left.

Optical Activity

The property of a molecule to rotate plane polarized light either to the right (dextrorotatory) or to the left (levorotatory).

Pyranose

A stable six-membered ring structure form of a monosaccharide, named after its similarity to pyran.

Furanose

A stable five-membered ring structure form of a monosaccharide, named after its similarity to furan.

Anomeric Carbon

The carbon atom that forms the chiral ring center, located at carbon 1 in aldoses and carbon 2 in ketoses.

Anomers

Isomers differing at the anomeric carbon, classified as $\alpha$ when the hydroxyl group is below the plane and $\beta$ when it is above the plane.

Epimers

Isomers that differ in configuration of the hydroxyl ($-OH$) and hydrogen ($-H$) groups specifically at carbon atoms 2, 3, or 4 of glucose, such as mannose and galactose.

Deoxy Sugar

A carbohydrate in which a hydroxyl group on the ring structure has been replaced by a hydrogen atom, such as 2-deoxyribose.

Amino Sugar

A derivative of a sugar containing an amino group, such as glucosamine, galactosamine, and mannosamine, found in glycoproteins, glycolipids, and certain antibiotics.

Reducing Sugar

A carbohydrate with a free aldehyde or ketone group capable of being oxidized to a carboxylic acid, reducing $Cu^{2+}$ in Benedict's reagent to a $Cu^+$ precipitate.

Glucose

The most abundant monosaccharide in the body that serves as the primary fuel source for the brain.

Fructose

The sweetest naturally occurring monosaccharide, found in fruits, vegetables, and honey.

Galactose

A monosaccharide that couples with glucose to form lactose and is converted by the body into glucose for energy.

Maltose

A disaccharide composed of two glucose units joined together, found in germinating grains.

Lactose

A disaccharide composed of glucose bonded to galactose, commonly known as milk sugar.

Sucrose

A non-reducing disaccharide composed of glucose bonded to fructose, commonly referred to as table sugar.

Cellulose

A linear homopolysaccharide consisting of $\beta 1,4$-linked glucose molecules that acts as a structural element in plants and is undigestible by mammals.

Starch

A plant storage homopolysaccharide composed of $\alpha 1,4$-linked glucose units with $\alpha 1,6$ branches every 12 to 20 residues, comprising unbranched amylose and branched amylopectin.

Glycogen

A highly branched storage homopolysaccharide in mammals made of $\alpha 1,4$-linked glucose units with $\alpha 1,6$ branch points every 8 to 12 residues.

Inulin

A starch derivative found in the roots of certain plants that hydrolyzes to fructose and is used to measure glomerular filtration rate.

Chitin

A structural homopolysaccharide made of $\beta 1,4$-linked N-acetylglucosamine (GlcNAc) units that forms exoskeletons of crustaceans and insects.

Glycosaminoglycans

Heteropolysaccharides containing amino sugars and uronic acid that retain large amounts of water to lubricate joints and mucous secretions.

Glycoprotein

Membrane-bound proteins attached to carbohydrate chains that lack uronic acid.