Deck 7: Carbohydrates and Glycobiology

Question 1

D-Glucose is called a reducing sugar because it undergoes an oxidation-reduction reaction at the anomeric carbon. One of the products of this reaction is:

A) D-galactose.
B) D-gluconate.
C) D-glucuronate.
D) D-ribose.
E) muramic acid.

Answer 1

B

Question 2

Which pair is epimeric?

A) D-glucose and D-glucosamine
B) D-glucose and D-mannose
C) D-glucose and L-glucose
D) D-lactose and D-sucrose
E) L-mannose and L-fructose

Answer 2

B

Question 3

When two carbohydrates are epimers:

A) one is a pyranose, the other a furanose.
B) one is an aldose, the other a ketose.
C) they differ in length by one carbon.
D) they differ only in the configuration around one carbon atom.
E) they rotate plane-polarized light in the same direction.

Answer 3

D

Question 4

Which monosaccharides is NOT a carboxylic acid?

A) 6-phospho-gluconate
B) gluconate
C) glucose
D) glucuronate
E) muramic acid

Question 5

The basic structure of a proteoglycan consists of a core protein and a:

A) glycolipid.
B) glycosaminoglycan.
C) lectin.
D) lipopolysaccharide.
E) peptidoglycan.

Question 6

Which pair is anomeric?

A) D-glucose and D-fructose
B) D-glucose and L-fructose
C) D-glucose and L-glucose
D) $\alpha$ -D-glucose and $\beta$ -D-glucose
E) $\alpha$ -D-glucose and $\beta$ -L-glucose

Question 7

Following complete hydrolysis of a sample of glycogen and a sample of cellulose, which statement must be TRUE?

A) The glycogen sample is more soluble than the cellulose sample.
B) The cellulose sample is more soluble than the glycogen sample.
C) Both samples consist of a mixture of $\alpha$ -D-glucose and $\beta$ -D-glucose.
D) The glycogen sample has a higher ratio of $\alpha$ -D-glucose than the cellulose sample.
E) The cellulose sample contains only $\beta$ -D-glucose.

Question 8

Which statement about starch and glycogen is FALSE?

A) Amylose is unbranched; amylopectin and glycogen contain many ( $\alpha$ 1 $\rightarrow$ 6) branches.
B) Both are homopolymers of glucose.
C) Both serve primarily as structural elements in cell walls.
D) Both starch and glycogen are stored intracellularly as insoluble granules.
E) Glycogen is more extensively branched than starch.

Question 9

The reference compound for naming D and L isomers of sugars is:

A) fructose.
B) glucose.
C) glyceraldehyde.
D) ribose.
E) sucrose.

Question 10

Which compound is NOT a reducing sugar?

A) fructose
B) glucose
C) glyceraldehyde
D) ribose
E) sucrose

Question 11

Hemoglobin glycation is a process where _____ is _____ attached to hemoglobin.

A) glycerol; covalently
B) glucose; enzymatically
C) glucose; nonenzymatically
D) N-acetyl-galactosamine; enzymatically
E) galactose; nonenzymatically

Question 12

To possess optical activity, a compound must be:

A) a carbohydrate.
B) a hexose.
C) asymmetric.
D) colored.
E) D-glucose.

Question 13

Which of the following monosaccharides is NOT an aldose?

A) erythrose
B) fructose
C) glucose
D) glyceraldehyde
E) ribose

Question 14

Which statement about hydrogen bonding in glycogen and cellulose is TRUE?

A) Glycogen forms more internal H-bonds than cellulose.
B) Extensive internal hydrogen bonding makes cellulose more water soluble than glycogen.
C) Extensive hydrogen bonding with water makes cellulose more soluble than glycogen.
D) Glycogen primarily forms hydrogen bonds within a single chain.
E) The hydrogen bonding in cellulose favors a helical conformation.

Question 15

Which pair is interconverted in the process of mutarotation?

A) D-glucose and D-fructose
B) D-glucose and D-galactose
C) D-glucose and D-glucosamine
D) D-glucose and L-glucose
E) $\alpha$ -D-glucose and $\beta$ -D-glucose

Question 16

From the abbreviated name of the compound Gal( $\beta$ 1 $\rightarrow$ 4)Glc, we know that:

A) C-4 of glucose is joined to C-1 of galactose by a glycosidic bond.
B) the compound is a D-enantiomer.
C) the galactose residue is at the reducing end.
D) the glucose is in its pyranose form.
E) the glucose residue is the $\beta$ anomer.

Question 17

Which compound is a heteropolysaccharide?

A) cellulose
B) chitin
C) glycogen
D) hyaluronate
E) starch

Question 18

When forming the disaccharide maltose from two glucose monosaccharides:

A) water is eliminated.
B) a hemiacetal is converted to an acetal.
C) the resulting dissacharide is no longer a reducing sugar.
D) water is eliminated and a hemiacetal is converted to an acetal.
E) None of the answers is correct.

Question 19

Starch and glycogen are both polymers of:

A) fructose.
B) glucose1-phosphate.
C) sucrose.
D) $\alpha$ -D-glucose.
E) $\beta$ -D-glucose.

Question 20

When the linear form of glucose cyclizes, the product is a(n):

A) anhydride.
B) glycoside.
C) hemiacetal.
D) lactone.
E) oligosaccharide.

Question 21

Which statement is NOT true regarding phosphorylated sugar?

A) It is trapped inside the cell membrane.
B) It is relatively stable at neutral pH.
C) It is activated for subsequent chemical transformation
D) It can be a component of a nucleotide.
E) All of the statements are true.

Question 22

Which arrow CORRECTLY identifies the atom that will become the anomeric carbon?

A) A
B) B
C) C
D) D
E) E

Question 23

Why is it surprising that the side chains of tryptophan residues in lectins can interact with sugars?

A) because the side chain of tryptophan is hydrophilic and sugars are hydrophobic
B) because the side chain of tryptophan is (-) charged and sugars are generally (+) charged or neutral
C) because the side chain of tryptophan can make hydrogen bonds and sugars cannot
D) because the side chain of tryptophan is hydrophobic and sugars are generally hydrophilic
E) None of the answers is correct.

Question 24

Which statement about heparan sulfate is NOT true?

A) Sulfation of heparan sulfate to form NS domains is important for its role as an anticoagulant.
B) Heparan sulfate can promote protein-protein interactions via the NS domains.
C) The secondary structure of heparan sulfate is completely random.
D) The NA domains of heparan sulfate contain no sulfation.
E) The core repeating structure of heparan sulfate is made up of alternating GlcNAc and GlcA.

Question 25

During which process are chemical bonds NOT broken?

A) mutarotation
B) interconverting between two configurations
C) interconverting between two conformations
D) interconverting between two anomers
E) None of the answers is correct: all involve breaking a chemical bond.

Question 26

Which monosaccharide is NOT a six-carbon monosaccharide?

A) fructose
B) ribose
C) mannose
D) glucose
E) galactose

Question 27

Which statement is NOT a reason that it is difficult to study oligosaccharide composition from biological systems?

A) Oligosaccharides are often branched.
B) Oligosaccharides often have a high negative charge density.
C) Oligosaccharides have a variety of linkages .
D) Oligosaccharides have too much conformational flexibility.
E) There are no specific glycosidase enzymes that can be used to selectively digest oligosaccharides.

Question 28

Which compound(s) is/are a dominant feature of the outer membrane of the cell wall of gram-negative bacteria?

A) amylose
B) cellulose
C) glycoproteins
D) lipopolysaccharides
E) lipoproteins

Question 29

Which reason is the MOST plausible for why most hexoses of living organisms are D isomers?

A) D isomers are more energetically favorable.
B) D isomers are also used by amino acids.
C) Sugars must be opposite isomers from amino acids.
D) Evolving enzymes were made to remain with an initial preference.
E) Evolving enzymes switch preference often to find the best isomer.

Question 30

Based on the form of the cyclic sugar shown below in a Haworth projection, which Fischer projection formula could have formed this structure?

Question 31

The biochemical property of lectins that is the basis for most of their biological effects is their ability to bind to:

A) amphipathic molecules.
B) hydrophobic molecules.
C) specific lipids.
D) specific oligosaccharides.
E) specific peptides.

Question 32

The two monosaccharides shown below could BEST be described as:

A) ketoses.
B) anomers.
C) rotamers.
D) epimers.
E) enantiomers.

Question 33

It is useful to analyze hemoglobin glycation to determine a(n):

A) single-time measurement of blood glucose levels.
B) single-time measurement of blood glycogen levels.
C) average blood glucose level over days or weeks.
D) average blood glycogen level over days or weeks.
E) None of the answers is correct.

Question 34

When drawing a Haworth perspective formula from a Fisher projection, which statement is TRUE regarding anomers?

A) It is $\alpha$ if the hydroxyl group on the anomeric carbon is up.
B) It is $\alpha$ if the hydroxyl group on the anomeric carbon is down
C) It is $\alpha$ if the hydroxyl group on the anomeric carbon on the same side of the ring as the C6
D) It is $\alpha$ if the hydroxyl group on the anomeric carbon on the opposite side of the ring as the C6
E) None of the answers is correct.

Question 35

In glycoproteins, the carbohydrate moiety is always attached through the amino acid residues:

A) asparagine, serine, or threonine.
B) aspartate or glutamate.
C) glutamine or arginine.
D) glycine, alanine, or aspartate.
E) tryptophan, aspartate, or cysteine.

Question 36

Which technique is NOT commonly used to study oligosaccharide structures?

A) x-ray crystallography
B) matrix-assisted laser desorption/ionization mass spectroscopy (MALDI-MS)
C) nuclear magnetic resonance (NMR)
D) complete chemical synthesis
E) oligosaccharide microarrays

Question 37

Which modification CANNOT be made to a sugar molecule by an organism?

A) oxidation of the carbonyl carbon
B) replacing a hydroxyl group with an amino group
C) oxidizing a carbon atom to a carboxyl group
D) replacing a hydroxyl group with a hydrogen atom.
E) All of the answer choices are possible sugar derivatives.

Question 38

A glycoconjugate molecule may include a carbohydrate as well as:

A) an amino acid.
B) a lipid.
C) a saccharide.
D) both an amino acid and a lipid.
E) an amino acid, a lipid, and a saccharide.

Question 39

Which statement concerning sialic acid residues on glycoproteins is TRUE?

A) Sialic residues on erythrocytes are recognized by lectins, leading to removal of the erythrocytes.
B) Sialic residues on ceruloplasmin are recognized by lectins, leading to removal of ceruloplasmin.
C) Sialic residues are removed by neuraminidases.
D) The antiviral drug oseltamavir accelerates the removal of sialic acid residues.
E) All of the statements are true.

Question 40

In a(n) _____ the carbonyl group is at the end of the carbon chain, but in a(n) _____ the carbonyl group can be at any other position.

A) aldose; ketose
B) ketose; aldose
C) hexose; heptose
D) aldose; hexose
E) ketose; tetrose

Question 41

In most cases, in order for an informational carbohydrate to become a biologically active molecule, it must:

A) be an asymmetric molecule.
B) contain a reducing sugar.
C) contain an O-glycosidic bond.
D) be covalently joined to a protein or lipid.
E) be present in the extracellular matrix.

Question 42

Which statement about free glucose storage is FALSE?

A) Glucose is insoluble and cannot contribute to the osmotic balance of the cell.
B) Glycogen has an intracellular concentration of 0.1 $\mu$ M, equivalent to a glucose concentration of 0.4 M.
C) The free energy difference between intra- and extracellular free glucose would be difficult to overcome for glucose uptake by the cell.
D) The concentration gradient of intra- and extracellular glucose would be prohibitively large.
E) All statements are true.

Question 43

The polysaccharide chitin is MOST chemically similar to:

A) cellulose.
B) dextran.
C) glycogen.
D) starch.
E) amylose.

Question 44

Which disaccharide does NOT have an anomeric carbon available for oxidation?

A) Glc ( $\alpha$ 1 $\leftrightarrow$ 1 $\alpha$ ) Glc
B) Glc ( $\alpha$ 1 $\leftrightarrow$ 2 $\beta$ ) Fru
C) Fru ( $\beta$ 2 $\leftrightarrow$ 1 $\alpha$ ) Glc
D) both Glc ( $\alpha$ 1 $\leftrightarrow$ 2 $\beta$ ) Fru and Fru ( $\beta$ 2 $\leftrightarrow$ 1 $\alpha$ ) Glc
E) None of the above

Question 45

Which statement about dextrans is FALSE?

A) Dextrans are bacterial and yeast polysaccharides.
B) All dextrans are made up of ( $\alpha$ 1 $\rightarrow$ 4)-linked poly-D-glucose.
C) All dextrans have ( $\alpha$ 1 $\rightarrow$ 3) branches.
D) Some dextrans have ( $\alpha$ 1 $\rightarrow$ 2) branches.
E) All statements are true.

Question 46

Which statement is FALSE about the enzyme lysozyme?

A) It is the active ingredient in penicillin.
B) It is found in human tears.
C) It is produced by some bacterial viruses.
D) It hydrolyzes the ( $\beta$ 1 $\rightarrow$ 4) glycosidic bond of peptidoglycan.
E) It causes osmotic lysis of bacterial cells.

Question 47

Why are ruminant animals like cows able to digest cellulose?

A) Their teeth are able to grind the polysaccharide into smaller saccharides.
B) Their stomachs secrete the enzyme cellulose.
C) They have a stomach compartment that houses symbiotic microorganisms that can hydrolyze cellulose.
D) Their small intestine contains an environment suitable to hydrolyze cellulose.
E) All animals can digest cellulose.

Question 48

In amylose, the most stable structure is a _____, which is stabilized by _____.

A) coiled helix; interchain hydrogen bonds
B) coiled helix; interchain covalent branching
C) coiled helix; hydrogen bonds to surrounding water molecules
D) straight, extended chain; interchain hydrogen bonds
E) straight, extended chain; hydrogen bonds to surrounding water molecules

Question 49

Which statement about cellulose is TRUE?

A) Cellulose is the main storage polysaccharide of animal cells.
B) Cellulose is a highly branched polysaccharide.
C) Cellulose is a homopolysaccharide.
D) Cellulose glucose residues contain the same configuration as amylose glucose residues.
E) Cellulose cannot be broken down by invertebrate animals.

Question 50

Which glycosaminoglycan is found in the synovial fluid of joints?

A) chondroitin sulfate
B) dermatan sulfate
C) hyaluronan
D) keratin sulfate
E) heparan sulfate

Question 51

What is the CORRECT name for the linkage between these monosaccharide derivatives?

A) ( $\alpha$ 1 $\rightarrow$ 4)
B) ( $\beta$ 1 $\rightarrow$ 4)
C) (1 4)
D) ( $\alpha$ 1 $\rightarrow$ $\beta$ 4)
E) ( $\alpha$ 1 $\rightarrow$ $\alpha$ 4)

Question 52

What possible benefits are provided by extended conformation that the heteropolysaccharide glycosaminoglycans assume in solution?

A) The repulsive forces of densely packed negative charges are minimized.
B) The hydrophobic portions of the molecules may pack closely together to maximize van der Waals forces.
C) The patterns of sulfated and nonsulfated sugar residues are more easily recognized by their respective ligands.
D) The repulsive forces of densely packed negative charges are minimized, and the hydrophobic portions of the molecules may pack closely together to maximize van der Waals forces.
E) The repulsive forces of densely packed negative charges are minimized, and the patterns of sulfated and nonsulfated sugar residues are more easily recognized by their respective ligands.

Question 53

The difference in interchain stability between the polysaccharides glycogen and cellulose is due to:

A) the different glycosidic linkages of the molecules.
B) the different hydrogen bonding partners of the individual chains.
C) the incorporation of complex ions in the three dimensional structures of both polysaccharides.
D) both the different glycosidic linkages of the molecules and the different hydrogen bonding partners of the individual chains.
E) None of the answers is correct.

Question 54

Which statement provides the MOST compelling reason to devote resources to study cellulose-degrading enzymes?

A) Humans could use cellulose as a food source.
B) Biomass could be converted to crude oil under high pressure.
C) Symbiotic microorganisms in digestive tracts could be used as treatments in some GI tract diseases.
D) Biomass could be converted more easily to bioenergy.
E) None of the answers is correct.

Question 55

Which statement is FALSE regarding proteoglycans?

A) Both syndecans and glypicans can be shed into the extracellular space.
B) Proteoglycan shedding is unregulated in cells.
C) A protease or phospholipase is responsible for releasing proteoglycans.
D) Proteoglycan shedding is activated in cancerous cells.
E) Cell features such as proteoglycans can be changed quickly.

Question 56

Which commonality does NOT exist between peptides, nucleic acids, and poly- and oligosaccharides?

A) They are all synthesized from a template.
B) They are all information-carrying molecules.
C) They are all created from multiple building blocks.
D) The sequence of monomers is important for function.
E) All of the answer choices are commonalities between peptides, nucleic acids, and poly- and oligosaccharides.

Question 57

A solution of the heteropolysaccharide _____ can be heated and cooled to form a three-dimensional matrix that traps water and supports the electrophoretic separation of nucleic acids.

A) dextrose
B) agarose
C) glycosaminoglycans
D) amylose
E) cellulose

Question 58

Polysaccharides CANNOT be used by cells:

A) as fuel storage molecules.
B) for structural elements in cell walls.
C) for structural elements in animal exoskeletons.
D) for the extracellular matrix in animal cells.
E) All of the answers are correct.

Question 59

Which polysaccharide(s) can the enzyme $\alpha$ -amylase break?

A) glycogen
B) starch
C) cellulose
D) both glycogen and cellulose
E) both glycogen and starch

Question 60

Which polysaccharide is NOT a homopolysaccharide?

A) glycogen
B) chitin
C) amylose
D) glycosaminoglycan
E) dextran

Question 61

Why is methyl iodide used in the classical method of exhaustive methylation to determine the positions of glycosidic bonds in a linear polysaccharide?

A) All free hydroxyls become unstable, allowing hydrolysis of only glycosidic bonds to occur in acid.
B) All free hydroxyls become stable, allowing hydrolysis of only glycosidic bonds to occur in acid.
C) All glycosidic bonds react with methyl iodide.
D) All glycosidic bonds become stable for treatment with acid.
E) All glycosidic bonds are hydrolyzed with methyl iodide.

Question 62

Which sequence is the CORRECT one for leukocyte extravasion in the inflammatory response?

A) integrin binding $\rightarrow$ selectin binding $\rightarrow$ adhesion $\rightarrow$ arrest $\rightarrow$ extravasion
B) adhesion $\rightarrow$ integrin binding $\rightarrow$ selectin binding $\rightarrow$ arrest $\rightarrow$ extravasion
C) selectin binding $\rightarrow$ integrin binding $\rightarrow$ adhesion $\rightarrow$ arrest $\rightarrow$ extravasion
D) integrin binding $\rightarrow$ adhesion $\rightarrow$ selectin binding $\rightarrow$ arrest $\rightarrow$ extravasion
E) selectin binding $\rightarrow$ adhesion $\rightarrow$ integrin binding $\rightarrow$ arrest $\rightarrow$ extravasion

Question 63

Assuming 20 common amino acids and 20 different monosaccharide subunits that are available for construction of polypeptides and oligosaccharides, respectively, compare the possible variations of these macromolecules using a hypothetical hexameric oligomer.

A) 20⁶ possible variations for both polypeptides and oligosaccharides
B) 6²⁰ variations for both polypeptide and oligosaccharides
C) 20⁶ variations for polypeptides and orders of magnitude greater for oligosaccharides
D) 20⁶ variations for oligosaccharides and orders of magnitude greater for polypeptides
E) It cannot be determined from the information given.

Question 64

_____ is the determination of the full component and function of sugar-containing molecules in a cell or tissue.

A) Genomics
B) Proteomics
C) Glycomics
D) Metabolomics
E) Lipidomics

Question 65

What strategy do cells use to overcome the modest affinity between an oligosaccharide and an individual CBD of a lectin?

A) lectin multivalency
B) expressing multiple lectin receptors
C) placing multiple CBDs on a single lectin molecule
D) both lectin multivalency and placing multiple CBDs on a single lectin molecule
E) lectin multivalency, expressing multiple lectin receptors, and placing multiple CBDs on a single lectin molecule

Question 66

Enzymatic hydrolysis of a purified polysaccharide with a glycosidase that cleaves specifically usually occurs before analysis by:

A) NMR and mass spectrometry.
B) ion-exchange chromatography.
C) gel-filtration chromatography.
D) lectin-affinity chromatography.
E) gas-liquid chromatography.

Question 67

_____ are secreted or membrane proteins that contain large numbers of O-linked oligosaccharide chains.

A) Gangliosides
B) Mucins
C) Glycins
D) Aminoglycans
E) Immunoglobulins

Question 68

Which statement accurately describes the interactions between the molecules thrombin, antithrombin, and heparan sulfate?

A) In the absence of heparan sulfate, antithrombin binds tightly to thrombin, inhibiting blood coagulation.
B) In the absence of heparan sulfate, antithrombin cannot bind to thrombin, inhibiting blood coagulation.
C) In the presence of heparan sulfate, antithrombin binds tightly to thrombin, inhibiting blood coagulation.
D) In the presence of heparan sulfate, antithrombin cannot bind to thrombin, enabling blood coagulation.
E) In the presence of heparan sulfate, antithrombin binds tightly to thrombin, enabling blood coagulation.

Question 69

Which type of protein interaction is NOT one with the NS domains of heparan sulfate?

A) conformational activation
B) cell-surface localization/concentration
C) enhanced protein-protein interaction
D) binding extracellular signaling molecules
E) All of the answer choices are types of protein interaction with heparan sulfate.

Question 70

About what percentage of mammalian proteins are glycosylated?

A) 5%
B) 15%
C) 50%
D) 90%
E) 95%

Question 71

The antiviral drugs oseltamivir (Tamiflu) and zanamivir (Relenza) do NOT work by:

A) inhibiting the viral enzyme that trims the host cell's oligosaccharides.
B) causing the viral particles to aggregate.
C) competing with the host cell's oligosaccharides for binding.
D) preventing the release of viruses from the infected cell.
E) All of the answers are correct.

Question 72

The severalfold greater incidence of gastric ulcers in _____ is due in part to a surface lectin in the bacterium Helicobacter pylori.

A) men versus women
B) people with a certain blood type
C) people of a certain age
D) people with autoimmune diseases
E) None of the answers is correct.

Question 73

A microarray of oligosaccharides can be used to determine:

A) specificity of lectin binding.
B) affinity of lectin binding.
C) conformational flexibility of lectin binding.
D) both specificity and affinity of lectin binding.
E) both specificity and conformational flexibility of lectin binding.

Question 74

Which factor is NOT a part of determining the complete structure of an oligosaccharide or polysaccharide?

A) determination of linear sequence
B) determination of lectin partners
C) determination of branching positions
D) determination of glycosidic linkages
E) determination of monosaccharide configuration

Question 75

_____ could be used to determine human blood group type.

A) Lipopolysaccharides
B) Globoside
C) Glycoproteins
D) Lipoproteins
E) Mucins

Question 76

Oligosaccharides differ from nucleic acids and proteins in that oligosaccharides are commonly:

A) branched.
B) polymeric.
C) acidic.
D) basic.
E) None of the answers is correct.

Question 77

High-performance liquid chromatography (HPLC) can be used to determine the:

A) position(s) of glycosidic bonds in a polysaccharide.
B) sequence of monosaccharides from a polysaccharide.
C) sequence of monosaccharides, as well as position and configuration of glycosidic bonds.
D) types and amounts of monosaccharide units in a polysaccharide.
E) None of the answers is correct.

Question 78

Under what circumstance might an organism's patterns of glycosylation NOT be altered?

A) development
B) genetic diseases
C) cancer
D) cell differentiation
E) All of the answers are correct.

Question 79

Several types of human joint and skeletal defects are a result of a defect in a biosynthetic enzyme responsible for synthesis of:

A) glycosaminoglycans.
B) glycoproteins.
C) glycolipids.
D) lipopolysaccharides.
E) glycosphingolipids.

Question 80

Which description of a ganglioside is MOST accurate?

A) the dominant surface feature of gram-negative bacteria.
B) the dominant surface feature of gram-positive bacteria.
C) an oligosaccharide chain attached to a newly synthesized protein in the ER
D) a membrane lipid in which the polar head group is a complex oligosaccharide containing at least one sialic acid
E) a membrane lipid in which the oligosaccharide is attached to a mucin