BioChemistry: Chapter 7 Learning Curve

How is chitin different from cellulose? a. Chitin has acetylated amino groups on C-2 of the glucose units; cellulose does not. b. Chitin has an amino group on C-3 and has (α1->4) linkages; cellulose has (β1->4) linkages. c. Chitin is a heteropolysaccharide; cellulose is a homopolysaccharide. d. Structurally, chitin and cellulose are identical; however, chitin is found in insects and cellulose in plants.

a. Chitin has acetylated amino groups on C-2 of the glucose units; cellulose does not.

What is the main benefit of storing glucose in a cell as a polysaccharide (e.g. glycogen) instead of a s free glucose? a. Compared to the same number of free glucose molecules, a polysaccharide has far less effect on osmolarity. b. The polysaccharide take up less physical space. c. The polysaccharide has more charged groups, making it more soluble. d. The polysaccharide is less susceptible to undesired oxidation.

a. Compared to the same number of free glucose molecules, a polysaccharide has far less effect on osmolarity.

How are glycogen and amylopectin different? a. Structurally they are the same, but glycogen is more compact with more extensive branching. b. The monosaccharide units are joined by different kinds of O-glycosidic bonds. c. Glycogen is a heteropolysaccharide; amylopectin is a homopolysaccharide. d. Amylopectin has more reducing ends than glycogen.

a. Structurally they are the same, but glycogen is more compact with more extensive branching.

Which statement is false about the binding of lectins to their carbohydrate ligands? a. Usually the carbohydrate forms a transient covalent bond to the lectin. b. A given lectin may have more than one carbohydrate binding domain (CBD). c. Binding can involve hydrophobic interactions, hydrogen bonding, and ionic interactions. d. The binding can be highly ligand-specific.

a. Usually the carbohydrate forms a transient covalent bond to the lectin.

What is another word for polysaccharide? a. glycan b. glycosylate c. glycoside d. glyceroside

a. glycan

All of the following statements are true about lactose except _____. a. its abbreviated name is Glc(β1->4)Gal b. it yields D-galactose and D-glucose upon hydrolysis c. it is a disaccharide d. it can be designated β-D-galactopyranosyl-(1->4)-β-D-glucopyranose

a. its abbreviated name is Glc(β1->4)Gal

In the synthesis and metabolism of carbohydrates, the intermediates are very often _____. a. phosphorylated sugar derivatives b. standard linear monosaccharides c. aldonic acids d. monosaccharides linked top lipid molecules

a. phosphorylated sugar derivatives

Which of the following statements is true regarding glycogen and amylopectin? a. Both are polymers of (α1->6)-linked subunits of glucose, with (α1->4)-linked branches. b. Both are branched polymers of glucose, but glycogen is more extensively branched. c. Glycogen is a form of energy storage in plants, whereas starch is an energy storage form in animals. d. All of the above. e. The first two answers are correct.

b. Both are branched polymers of glucose, but glycogen is more extensively branched.

What is the benefit of branching in storage polysaccharides? a. It allows tighter packaging of the polysaccharide. b. It creates more non-reducing ends for rapid access to glucose. c. It forces the glycosidic linkages to be all α−conformation. d. α−1,6 linkages are easier to break than α−1,4 linkages. e. None of these are actual benefits.

b. It creates more non-reducing ends for rapid access to glucose.

Where are glycolipids and glycoproteins found on the plasma membrane? a. on the inner face of the plasma membrane b. on the outer face of the plasma membrane c. The first two answers are correct. d. none of the above

b. on the outer face of the plasma membrane

Which statement does not apply to glucose? a. has 4 chiral centers b. pentose c. Enantiomers are possible. d. aldose

b. pentose

Which is not a copolymer of alternating uronic acid and amino sugar residues? a. chondrotin 4-sulfate b. heparin c. keratan sulfate d. hyaluronan

c. keratan sulfate

How many reducing ends are present in a molecule of glycogen? a. None. Glycogen is a non-reducing polysaccharide. b. 2 c. n+1, where n equals the number of branches. d. 1

d. 1

In a highly ordered theoretical polysaccharide, where branching occurs every five glucose residues, how many non-reducing ends would be present in a polymer consisting of 155 glucose molecules? a. 1 b. 4 c. 8 d. 16 e. 31

d. 16

Glycine and alanine can form two possible dipeptides: gly-ala and ala-gly. How many possible disaccharides can be formed from two molecules of α D-glucopyranose, using O-glycosidic bonds? a. 1 b. 2 c. 4 d. 5

d. 5

Which of the following statements is false regarding the sugar code? a. Sulfation of one or more residues in an oligosaccharide chain can in crease the number os possible oligosaccharides by two orders of magnitude. b. It is reasonable to assume that 20 different monosaccharide subunits are available. c. Cells use specific oligosaccharides to encode important information about intracellular targeting of proteins. d. Like nucleic acids and proteins, oligosaccharides do not form branched structures.

d. Like nucleic acids and proteins, oligosaccharides do not form branched structures.

Which of the following statements is true about glycomics? a. Mass spectrometry is relied upon in this line of research. b. It offers potential insights into normal patterns of glycosylation and the ways in which they are altered during development or in genetic diseases or cancer. c. It is the systematic characterization of all of the carbohydrate components of a given cell or tissue. d. all of the above

d. all of the above

In the polysaccharide chitin, the glycosidic bonds are _____. a. all β-O-glycosidic linkages b. alternating α-O-glycosidic linkages c. random O-glycosidic linkages d. all β-O-glycosidic linkages

d. all β-O-glycosidic linkages

A major constituent of cotton and linen fabrics is _____. a. dextran b. agarose c. chitin d. cellulose

d. cellulose

Which of the following is not a reducing sugar? a. lactose b. glucose c. maltose d. sucrose

d. sucrose

The sequence of monosaccharides, as well as the position and configuration of glycosidic bonds can be determined by _____. a. NMR and mass spectrometry of separated oligosaccharides. b. enzymatic hydrolysis of separated oligosaccharides with specific glycosidases followed subjection of oligosaccharides to either methylation or enzymatic analysis c. subjecting a fully methylated carbohydrate to acid hydrolysis d. treatment of separated oligosaccharides with a strong acid e. The first two answers are correct.

e. The first two answers are correct.

Proteins and nucleic acid sequencing is often less complex than polysaccharide sequencing because _____. a. proteins and nucleic acids have unique ends (e.g. N-terminal and 5' end) for sequence initiation; polysaccharides do not b. proteins and nucleic acids are linear polymers whereas polysaccharides may be branches, which adds much complexity to sequencing c. O-glycosidic bonds are much harder to cleave than peptide or phosphodiester bonds d. many polysaccharides have an indefinite length due to the way they are biosynthesized

b. proteins and nucleic acids are linear polymers whereas polysaccharides may be branches, which adds much complexity to sequencing

What is the main structural difference between cellulose and amylose? a. Amylose is branched; cellulose is not branched. b. The monomer of amylose is glucose; the monomer of cellulose is fructose. c. Amylose has (α1->4) linkages; cellulose has (β1-4) linkages. d. Amylose has a definite molecular weight; cellulose chains vary in molecular weight.

c. Amylose has (α1->4) linkages; cellulose has (β1-4) linkages.

Which of the following is false regarding the antiviral drug oseltamivir? a. It inhibits viral sialidase by competing with the host cell's oligosaccharides for binding. b. It prevents the release of viruses from the infected cell. c. It is a noncompetitive inhibitor of neuraminidase. d. It is a sugar analog.

c. It is a noncompetitive inhibitor of neurominidase.