Chapter 11. Carbohydrates

Question 1

Molecules that have identical molecular formulas but differ in how the atoms are ordered. For instance, glyceraldehyde and dihydroxyacetone.

Answer 1

Constitutional isomer

Question 2

The study of the glycome, all of the carbohydrates and carbohydrate-associated molecules that cells produce. Like the proteome, the glycome is not static and can change, depending on cellular and environmental conditions.

Answer 2

Glycomics

Question 3

a monosaccharide whose C-1 carbon contains an aldehyde group.

Answer 3

Aldose

Question 4

A pair of molecules, each with more than one asymmetric center, that have opposite configurations at one such center but are not mirror images of each other; in the aldotetrose series, Derythrose and D-threose are diastereoisomers.

Answer 4

Diastereoisomer

Question 5

Reactions between an amino group in a protein not participating in a peptide bond and the aldehyde form of a carbohydrate. Such reactions frequently compromise protein function.

Answer 5

Advanced glycosylation product

Question 6

isomers of cyclic hemiacetals or hemiketals, with different configurations only at the carbonyl carbon; that carbon is known as the anomeric carbon.

Answer 6

Anomer

Question 7

an unbranched homopolysaccharide in plants, composed of glucose residues in α-1,4 linkage; the major structural polysaccharide in plants.

Answer 7

Cellulose

Question 8

Consists of two sugars joined by an O-glycosidic bond.

Answer 8

disaccharide

Question 9

The study of the synthesis and structure of carbohydrates and how carbohydrates are attached to and recognized by other molecules such as proteins.

Answer 9

Glycobiology

Question 10

single aldehydes or ketones that have two or more hydroxyl groups; the simplest carbohydrates.

Answer 10

Monosaccharide

Question 11

pairs of molecules with one or more chiral centers that are mirror images of each other.

Answer 11

Enantiomer

Question 12

a monosaccharide that has a ketone group as its most oxidized carbon.

Answer 12

Ketose

Question 13

a six-membered heterocyclic ring formed when a monosaccharide cyclizes to form a hemiacetal or a hemiketal; the six-membered, oxygen-containing ring is similar to that of pyran.

Answer 13

Pyranose

Question 14

a five-membered heterocyclic ring formed when a monosaccharide cyclizes to form a hemiacetal or a hemiketal; the five-membered oxygen-containing ring is similar to that of furan.

Answer 14

Furanose

Question 15

pairs of molecules with more than one asymmetric center that differ in configuration at only one such center; glucose and galactose are epimers, differing only in the configuration at C-4.

Answer 15

Epimer

Question 16

A readily mobilized storage form of glucose in which the glucose monomers are linked by α-1,4-glycosidic bonds and with branches (α-1,6-glycosidic bonds) at about every tenth residue.

Answer 16

Glycogen

Question 17

Forms of a specific protein that differ only in patterns of glycosylation.

Answer 17

Glycoform

Question 18

A protein that binds specific carbohydrate structures on neighboring cell surfaces.

Answer 18

Glycan-binding protein

Question 19

an extensive system of cytoplasmic membranes that comprises about half the total cell membrane. The region of the ER that binds ribosomes is called the rough ER while the region that is devoid of ribosomes is called the smooth ER.

Answer 19

Endoplasmic reticulum

Question 20

proteins that have a specific carbohydrate moiety attached.

Answer 20

Glycoprotein

Question 21

a lipid containing approximately 20 isoprene units that serves as a carrier of oligosaccharides destined to be attached to a protein, through a membrane.

Answer 21

Dolichol phosphate

Question 22

a compound formed by the reaction of an aldehyde functional group and a hydroxyl group; for example, the C-1 group of the open-chain form of glucose reacts with the C-5 hydroxyl group to form an intermolecular hemiacetal.

Answer 22

Hemiacetal

Question 23

carbohydrate composed of 2 to 10 or 12 monosaccharide units.

Answer 23

Oligosaccharide

Question 24

sugars that convert to a form with a free aldehyde group that is readily oxidized, thus reducing another compound.

Answer 24

Reducing sugar

Question 25

a covalent bond between an aldehyde or ketone function of a monosaccharide and an oxygen, nitrogen, or sulfur atom of another molecule. The most common glycosidic linkages are O-links between the anomeric carbon of a sugar and a hydroxyl group of another saccharide.

Answer 25

Glycosidic bond

Question 26

sugars that are not readily converted to a form with a free aldehyde group capable of reducing another compound. Such a conversion is prevented because the sugar forms a glycosidic bond with another compound.

Answer 26

Nonreducing sugar

Question 27

carbohydrates composed of large numbers of linear or branched monosaccharide units; homopolysaccharides are composed of large numbers of one type of sugar, while heteropolysaccharides contain more than one type.

Answer 27

Polysaccharide

Question 28

a compound formed by the reaction of a ketone group and a hydroxyl group; for example, the C-2 keto group of the open-chain form of fructose reacts with the C-5 hydroxyl group to form an intermolecular hemiketal.

Answer 28

Hemiketal

Question 29

any one of a number of specific enzymes that catalyze the formation of glycosidic bonds.

Answer 29

Glycosyltransferase

Question 30

A glycoprotein that is predominately carbohydrate. N-Acetylgalactosamine is usually the carbohydrate moiety bound to the protein in mucins, which serve as lubricants.

Answer 30

Mucin (mucoprotein)

Question 31

a heteropolysaccharide made of repeating disaccharide units and containing the amino sugar glucosamine or galactosamine.

Answer 31

Glycosaminoglycan

Question 32

plant proteins with a high affinity for specific sugar residues. As such, they are important probes of carbohydrate containing molecules.

Answer 32

Lectin

Question 33

a stack of membranous sacks in the cytoplasm which is the major sorting center for proteins which reside in cell membranes and the lumen of organelles.

Answer 33

Golgi complex

Question 34

proteins containing one or more covalently linked glycosaminoglycan chains. Cartilage proteoglycan contains keratan sulfate and chondroitin chains linked to a polypeptide backbone.

Answer 34

Proteoglycan

Question 35

a homopolysaccharide that is a storage form of glucose in plant chloroplasts; amylopectin, the branched form of starch, has approximately one α-1,6 linkage per thirty α-1,4 linkages, while amylose is unbranched, composed of glucose residues in α-1,4 linkage.

Answer 35

Starch

Question 36

carbohydrate-binding proteins that constrain immune-system cells to the site of injury in the inflammatory response.

Answer 36

Selectin

Question 37

Isomers in which the atoms are connected in the same order but differ in spatial arrangement.

Answer 37

stereoisomer