Denniston, 8e

Glossary of Key Terms in Chapter Sixteen

aldose (16.2) a sugar that contains an aldehyde (carbonyl) group.

amylopectin (16.6) a highly branched form of amylose; the branches are attached to the C-6 hydroxyl by (16) glycosidic linkage; a component of starch.

amylose (16.6) a linear polymer of -D-glucose in (14) glycosidic linkage that is a major component of starch; a polysaccharide storage form.

anomers (16.4) isomers of cyclic monosaccharides that differ from one another in the arrangement of bonds around the hemiacetal carbon.

Benedict’s reagent (16.4) a buffered solution of Cu2+ ions that can be used to test for reducing sugars.

carbohydrate (16.1) generally sugars and polymers of sugars; the primary source of energy for the cell.

cellulose (16.6) the most abundant organic compound in the world; a polymer of -D-glucose linked by (14) glycosidic bonds.

chiral carbon (16.3) a chiral carbon; a carbon bonded to four different groups.

chiral molecule (16.3) molecules capable of existing in mirror image forms.

diastereomer (16.3) stereoisomers that are not mirror images of one another; these typically occur when the molecule has more than one chiral carbon.

disaccharide (16.1) a sugar composed of two monosaccharides joined through an oxygen atom bridge.

enantiomers (16.3) stereoisomers that are nonsuperimposable mirror images of one another.

Fischer Projection (16.3) a two-dimensional drawing of a molecule, which shows a chiral carbon at the intersection of two lines with the horizontal lines representing bonds projecting out of the page and the vertical lines representing bonds that project into the page.

fructose (16.4) a ketohexose that is also called levulose and fruit sugar; the sweetest of all sugars, abundant in honey and fruit.

galactose (16.4) an aldohexose that is a component of lactose, milk sugar.

galactosemia (16.5) a human genetic disease caused by the inability to convert galactose to glucose-1-phosphate.

glucose (16.4) an aldohexose, the most abundant monosaccharide; it is a component of many disaccharides, such as lactose and sucrose, and polysaccharides, such as cellulose, starch, and glycogen.

glyceraldehyde (16.3) an aldotriose that is the simplest carbohydrate; phosphorylated forms of glyceraldehyde are important intermediates in cellular metabolic reactions.

glycogen (16.6) the glucose storage form of animals; a linear backbone of -D-glucose in (14) linkage, with numerous short branches attached to the C-6 hydroxyl group by (16) linkage.

glycosidic bond (16.1) the bond between the hydroxyl group of C-1 carbon of one sugar and a hydroxyl group of another sugar.

Haworth projections (16.4) a means of representing the orientation of substituent groups around a cyclic sugar molecule.

hemiacetal (16.4) the product of the reaction between an aldehyde and an alcohol.

hemiketal (16.4) the product of the reaction between a ketone and an alcohol.

heteropolysaccharide (16.6) a polysaccharide composed of two or more different monosaccharides.

hexose (16.2) a six carbon monosaccharide.

homopolysaccharide (16.6) a polysaccharide composed of identical monosaccharides.

ketose (16.2) a sugar that contains a ketone (carbonyl) group.

lactose (16.5) a disaccharide composed of -D-galactose and either - or -D-glucose in (14) glycosidic linkage; milk sugar.

lactose intolerance (16.5) the inability to produce the enzyme lactase, which degrades lactose to galactose and glucose.

maltose (16.5) a disaccharide composed of -D-glucose and either - or -D-glucose in (14) glycosidic linkage.

meso compound (16.3) a special case of stereoisomers that occurs when a molecule has two chiral carbons and each chiral carbon has identical substituents; these molecules are achiral because they have a plane of symmetry within the molecule.

monosaccharide (16.1) the simplest type of carbohydrate consisting of a single saccharide unit.

nonreducing sugar (16.5) a sugar that cannot be oxidized by Benedict’s reagent.

oligosaccharide (16.1) an intermediate-sized carbohydrate composed of from three to ten monosaccharides.

pentose (16.2) a five carbon monosaccharide.

polysaccharide (16.1) a large, complex carbohydrate composed of long chains of monosaccharides.

reducing sugar (16.4) a sugar that can be oxidized by Benedict’s reagent. This includes all monosaccharides and most disaccharides.

ribose (16.4) a five carbon monosaccharide that is a component of RNA and many coenzymes.

saccharide (16.1) a sugar molecule.

stereochemistry (16.3) the study of the spatial arrangement of atoms in a molecule.

stereoisomers (16.3) a pair of molecules having the same structural formulas and bonding patterns, but differing in the arrangement of the atoms in space.

sucrose (16.5) a disaccharide composed of -D-glucose and -D-fructose in (12) glycosidic linkage; table sugar.

tetrose (16.2) a four carbon monosaccharide.

triose (16.2) a three carbon monosaccharide.