Chapter 7

Disaccharide

A carbohydrate incorporating two simple sugars joined by glycosidic linkage

Ketose

A carbohydrate whose carbonyl group is a ketone

Aldose

A carbohydrate whose carbonyl group is an aldehyde

Oligosaccharide

A carbohydrate with moderate (~3 to ~10) number of monosaccharide units bound together by glycosidic bonds. No firmly defined boundary between "oligosaccharide" and "polysaccharide", but carbohydrate with more than 10 saccharide units starts to get into polysaccharide territory

Polysaccharide

A carbohydrate composed of many monosaccharides linked together.

Aldaric acid

A dicarboxylic acid derived from the oxidation of an aldose, where both ends are carboxylic acids

Furanose

A five-membered cyclic hemiacetal. The name derives from furan, a five membered cyclic ether. Furanoses are distinct from pyranoses, which is a six-membered cyclic hemiacetal

Haworth Projection

A graphical depiction of monosaccharides that clearly shows the stereochemistry at each carbon (at the expense of accurately depicting its conformation) Used for cyclic sugars (pyranoses and furanoses) Clearly indicates stereochemical arrangement of groups on ring (up/down) Not meant to accurately convey the ring conformation

Glycogen is...

A major storage form of carbohydrates in animals

Reducing sugar

A mono- or disaccharide which give a positive Tollens test. Practically, it refers to any mono- or disaccharide with a hemiacetal that can undergo ring-chain tautomerism Glycosides are NOT reducing sugar, since they are not in equilibrium with an aldehyde or ketone

Pentose

A monosaccharide with five carbons

Starch is...

A plant polysaccharide that is easily digested by humans Made up of two glucose polysaccharides: amylose and amylopectin

Pyranose

A six-membered cyclic monosaccharide hemiacetal

Saccharide

A sugar or sugar derivative Synonym of carbohydrate

Hexose

A sugar with six carbons, the most familiar being glucose. A hexose that bears an aldehyde (or masked aldehyde) is called an aldohexose A hexose bearing a keton is called a ketohexose

Gluconic acid is an...

Aldonic acid

Muramic acid is an...

Amino sugar

Alditol

An a cyclic alcohol derived from the reduction of an aldose

What are some components of BOTH N-acetylmuramic acid and N-acetyleneuraminic acid?

An amino group derivative (R1-NH—R2) Acetic acid

What is the relationship between alpha and beta compounds

Anomers Epimers Enantiomers

Which methods could be used to hydrolyze sucrose to invert sugar nonenzymatically in your kitchen at home?

Boil the sucrose solution in water. Add lemon juice to the solution in a warm water bath.

What are some components of N-acetylneuraminic acid

Carboxyl group at C1

Chitin...

Consists of N-acetylglucosamine residues Provides structural support for animals such as arthropods

Empirical formula of a carbohydrate

Cn(H2O)n

Fucose is a...

Deoxy sugar

D- and L- sugars are

Enantiomers

Alpha 1 to beta 2 glycosidic linkage

Formed by the OH group on the anomeric carbon and the OH group on the anomeric carbon. Ties together the anomeric carbons of the two monosaccharides

1-4 alpha glycosidic bond

Formed when the OH on the carbon 1 is below the glucose ring.

What is the primary function of lectins?

Facilitation of cell-to-cell contact

Glycoside

Fancy name for an acetal (or ketal) formed from a sugar. Formally, a glycoside is an acetal derived from condensation of the hemicacetal (or hemiketal) carbon of a sugar with the hydroxy group of another compound Resulting product IS NOT a reducing sugars since it isn't in equilibrium with an open-chain form

What major advantage does glucose oxidase offer over Fehling's reagent for measuring blood glucose?

Fehling's reagent is not specific to glucose, detecting other reducing sugars

Beta 1 - 4 linkage

Formed between carbon 1 of one monosaccharide and carbon 4 of the other monosaccharide Formed when OH is above the plane

What is a component of neither N-acetylmuramic acid and N-acetylneuraminic acid

Fructose

Glycogen...

Functions in fuel storage in animal cells Is the storage form of glucose in animals

Sugars that show mutarotation

Galactose Glucose Lactose

What are some components of N-acetylmuramic acid

Glucose Lactic acid

Determine which statements about glycosaminoglycans are true

Hyaluronan (hyaluronate) and keratin sulfate are examples of glycosaminoglycans Glycosaminoglycans contain a high negative charge density, which enables interaction with the aqueous environment

Starch...

Is a storage form of fuel in plant cells Is made up of two glucose polysaccharides, amylose and amylopectin

Which of these are possible components of glycosaminoglycans?

N-acetylglucosamine Uronic acid

Which statements about these carbohydrate derivatives are true?

N-acetylmuramic acid is a component of the repeating peptidoglycan unit of bacterial cell walls N-acetalneuraminic acid is a component of some cell membrane glycoproteins

L- in Fischer projection

OH on the bottom chiral center points to the left

D- in Fischer projection

OH on the bottom chiral center points to the right

True or False: L and D refer to the absolute configuration of a sugar

True

When does an Aldonic acid form?

When carbon 1 of a hexose is oxidized to a carboxylic acid

When does a uronic acid form?

When carbon 6 of a hexose is oxidized to a carboxylic acid

Cellulose...

Provides structural support for plants

Cellulose is...

Structural support for plants

Proteoglycans

Structure: glycosaminoglycans covalently joined to a protein at a Ser residue Location: extra cellular matrix; some are integral membrane proteins Functions: many functions, including cell adhesion

Peptidoglycan

Structure: heteropolymer of MurNAc and GlcNAc with peptide chain attached Location: bacterial cell wall Function: strength for cell envelope

Glycolipids

Structure: sphingolipid bound to an oligosaccharide Location: outer membrane lipids of cells Function: some are gangliosides that contribute to blood type

Glycoproteins

Structure: sugar covalently attached to protein through an O-linkage or N-linkage Location: part of proteins at outer surface of plasma membrane, in ECM, and in blood Function: many functions, including acting as hormones

Sugars the DO NOT show mutarotation

Sucrose Trehalose

Alpha configuration (at anomeric carbon)

The (OH) substituent on the anomeric carbon is facing opposite the CH2OH

Beta configuration (at anomeric carbon)

The OH substituent on the anomeric carbon is facing the same side as the CH2OH

How can the total blood glucose test measure total blood glucose?

The alpha anomer and beta anomer of glucose interconvert quickly

Glycosidic bond

The bond that links the anomeric carbon of a sugar to another compound

Anomeric carbon

The carbon of a cyclic sugar bearing a hemiacetal or acetal (hemiketal or metal) C1 in aldose C2 in fructose

Mutarotation

The change in optical rotation that occurs when a pure anomer equilibrates to the different anomer through ring-chain tautomerism

Ring-chain tautomerism

The equilibrium between linear and cyclic forms that occurs in aldoses and ketoses. Ring-chain tautomerism is possible when the cyclic form has a hemiacetal, but is not possible in glycosides (where the acetal and metals are "locked")

Select the statements that describe the characteristics of that allow chondroitin sulfate to occupy a much larger volume in solution.

The highly polar nature of chondroitin sulfate attracts numberous water molecules. Noncovalent interactions with a large number of water molecules increases its molecular volume Chondroitin sulfate has a high density of negative charges. To ensure adequate separation of negatively charges groups, chondroitin sulfate adopts an extended rod-like structure that increases its molecular volume in solution

Anomer

The name given to two diastereomeric monosaccharides that are epimers at the anomeric carbon. The two anomers are described with the terms alpha and beta

Epimer

Two sugars which differ in the configuration of a single chiral center. D glucose and D mannose are epimers, as are D mannose and D talose.

Cellulose could provide an abundant and cheap form of glucose for humans. Why is cellulose not a source of nutrients for humans>

Vertebrate enzymes are unable to hydrolyze (beta 1 - 4) linked glucose monomers Humans, and most vertebrates, lack the enzyme cellulase