Deck 7: Carbohydrates and the Glycoconjugates of Cell Surfaces

Question 1

A cyclic hemiacetal with a six-membered oxygen-containing ring is referred to as a(n):

A) aldehyde.
B) pyranose.
C) ketopentose.
D) furanose.
E) sorbitol.

Answer 1

B

Question 2

Which of the following is correctly paired with its most prevalent cyclization product?

A) fructose: pyranose
B) glucose: furanose
C) ribose: pyranose
D) galactose: does not cyclize
E) none of the above

Answer 2

C

Question 3

Mannose is an epimer of:

A) ribose
B) galactose
C) glucose
D) xylose.
E) fructose.

Answer 3

C

Question 4

The formation of cyclic structures in sugars with creation of an additional asymmetric center results from an alcohol reacting with a(n):

A) secondary alcohol.
B) phosphate group.
C) thiol group.
D) aldehyde or ketone.
E) primary alcohol.

Question 5

The enantiomer of D-mannose would be:

A) D-galactose.
B) L-glucose.
C) D-glucose.
D) L-mannose.
E) L-arabinose.

Question 6

As a result of mutarotation, D-glucose exists in all of the following forms EXCEPT:

A) L-glucopyranose.
B) β-anomer.
C) free aldehyde.
D) α-anomer.
E) all are true.

Question 7

Which of the following disaccharides contains an α (1→4) O-glycosidic bond?

A) sucrose
B) lactose
C) maltose
D) cellobiose
E) cellulose

Question 8

Carbohydrate characteristic chemical features include all EXCEPT:

A) the potential to form multiple hydrogen bonds.
B) the existence of one or more asymmetric centers.
C) the capacity to form polymeric structures.
D) the ability to exist in either linear or ring structures.
E) all are true.

Question 9

A constituent of the flavin coenzymes is

A) sorbitol
B) mannitol
C) xylitol
D) ribitol
E) glycerol

Question 10

Honey is characteristically composed predominantly of

A) sucrose
B) glucose and ribose
C) fructose and glucose
D) sucrose and sorbitol
E) all of the above

Question 11

A glycosidic bond would be present in:

A) β-D-galactosamine.
B) methyl-β-D-glucoside.
C) 2-deoxy-α-D-ribose.
D) β-D-glucose-6-phosphate.
E) α-D-fructose-1, 6-bisphosphate.

Question 12

All of the statements about the following pairs of sugars are correct EXCEPT:

A) Galactose and mannose are diastereomers.
B) L-galactose and D-galactose are enatiomers.
C) Glyceraldehyde and dihydroxyacetone are stereoisomers.
D) Glucose and mannose are epimers.
E) Glucose has fewer chiral centers than fructose.

Question 13

If carbon 1 is the carbonyl group of an aldohexose, which carbon determines if the sugar is a D- or L- stereoisomer?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 14

Which of the following sugars is an aldopentose?

A) galactose
B) ribulose
C) ribose
D) xylulose
E) mannose

Question 15

____ and ____ are glycosamines linked to three-carbon acids at the C-1 or C-3 positions, and components of the polysaccharides of cell higher organisms and bacterial cell walls.

A) Glucosides; galactosides
B) Muramic acid; neuraminic acid
C) Gluconic acid; glucuronic acid
D) Sorbitol; ribitol
E) None of the above

Question 16

β-D-glucopyranose in the chair form is the most widely occurring form of glucose in nature and it has the following characteristics EXCEPT:

A) forms a six-membered ring.
B) carbon 6 is above the plane of the chair.
C) all of the −OH groups are equatorial.
D) the anomeric carbon has a hydroxyl that is below the plane of the chair.
E) all axial positions are occupied by −H.

Question 17

All of the following are parts of the honeybee's processing of honey EXCEPT:

A) producing a small amount of gluconic acid.
B) concentrating the sugars to a supersaturated state.
C) conversion of some glucose and fructose into sucrose.
D) conversion of most of the fructose to the β-D-fructopyranose form.
E) producing an emulsion of glucose hydrate and fructose hydrate crystals in a thick syrup.

Question 18

Sugar alcohols include all of the following EXCEPT:

A) ribitol.
B) sorbitol.
C) fucose.
D) mannitol.
E) glycerol.

Question 19

Glucose most commonly forms which of the following structures?

A) a pyranose using the hydroxyl group on carbon 4
B) a pyranose using the hydroxyl group on carbon 5
C) a pyranose using the hydroxyl group on carbon 6
D) a furanose using the hydroxyl group on carbon 3
E) a furanose using the hydroxyl group on carbon 4

Question 20

Individuals with uncontrolled diabetes mellitus may have ____ levels of blood ____ so they test their blood for ____.

A) elevated; fructose; gluconic acid
B) depressed; glucose; oxidizing sugars
C) elevated; glucose; fructose
D) depressed; gluconic acid; reducing sugars
E) elevated; glucose; reducing sugars

Question 21

All of the following disaccharides are reducing sugars EXCEPT:

A) lactose.
B) maltose.
C) sucrose.
D) cellulose.
E) isomaltose.

Question 22

Mucopolysaccharides such as ____ form protective coats on animal cells.

A) chitin
B) cellulose
C) glycogen
D) hyaluronic acids
E) glucuronic acids

Question 23

All are true for cellulose and α-amylose EXCEPT:

A) Both are linear homopolymers of glucose.
B) Both have (1→4) linkages.
C) Both form extended ribbon most stable conformations.
D) Both have extensive intramolecular hydrogen bonding.
E) All are true.

Question 24

Which of the following statements about cellulose fiber is true?

A) It is a linear polymer of β (1→4) glycosidic linked glucose and galactose residues.
B) It is extremely susceptible to hydrolysis.
C) It is water-soluble.
D) It is made up of very weak microfibrils.
E) Intermolecular hydrogen bonds play a major role in stabilization of the microfibrils.

Question 25

Cellulose and chitin are similar in all of the following ways EXCEPT:

A) Both are polymers of glucose.
B) Both are structural polysaccharides.
C) Both have extended ribbon conformations.
D) Both have extensive hydrogen bonding.
E) All are true.

Question 26

The enzymes α-amylase and β-amylase can cleave the ____ bonds of amylopectin but not the ____ bonds.

A) α (1→6)-; α (1→4)-
B) β (1→6)-; β (1→4)-
C) α (1→4)-; β (1→4)-
D) α (1→4)-; α (1→6)-
E) α (1→6)-; β (1→4)-

Question 27

____ is typical of the oligosaccharide components found in beans, etc., that are not digested in the stomach, but are digested by bacteria in the intestines causing flatulence.

A) Melezitose
B) Amygdelin
C) Laetrile
D) Stachyose
E) Dextrantriose

Question 28

In plant cells, starch is hydrolyzed by ____ to release ____ and a starch molecule with ____.

A) starch phosphorylase; glucose-1-phosphate; one less glucose unit
B) salivary α-amylase; maltose 1-phosphate; two less glucose units
C) starch phosphorylase; maltose 1-phosphate; two less glucose units
D) α(1→6) glucosidase; glucose-6-phosphate; one less glucose unit
E) starch hydrolase; glucose; one less glucose unit

Question 29

Because osmotic pressure depends only on ____, the osmotic pressure is greatly reduced by formation of polysaccharide molecules from monosaccharide molecules.

A) molecular weight
B) number of hydroxyl groups
C) numbers of molecules
D) numbers of hydrogen bonds
E) none are true

Question 30

Which of the following explains why the disaccharide sucrose is not a reducing sugar?

A) the primary hydroxyl groups are oxidized to carboxylic acids
B) both anomeric carbons are involved in formation of the glycosidic bond
C) the glycosidic bond is in the α configuration
D) it is composed of a furanose and a pyranose
E) none of the above

Question 31

The cyclization of gluconic acid produces what type of structure?

A) lactam
B) lactone
C) pyranose
D) cyclic ether
E) none of the above

Question 32

All of the following are homodisaccharides EXCEPT:

A) lactose.
B) maltose.
C) isomaltose.
D) cellobiose.
E) all are homodisaccharides.

Question 33

Cellulose is homopolysaccharide composed of ______ linked together by ______ glycosidic bonds.

A) galactose; β-(1→4)
B) galactose; α-(1→4)
C) glucose; β-(1→4)
D) glucose; α-(1→4)
E) none of the above

Question 34

All are true statements about dextrans EXCEPT:

A) They are used in research laboratories as a support for column chromatography (Sephadex or BioGel).
B) They are repeating units of isomaltose.
C) The branches may be 1→2, 1→3 or 1→4 in various species.
D) They are an important component of dental plaque.
E) All are true.

Question 35

Cellulase is considered a(n) ____.

A) α-(1→4) glucosidase
B) β-(1→4) glucosidase
C) α-(1→6) glucosidase
D) β-(1→4) glucosidase
E) α-(1→1) glucosidase

Question 36

All of the following statements about the nature of glycogen are true EXCEPT:

A) It is a polysaccharide used for storage.
B) It is a branched polymer of linked glucose residues.
C) It has all non-reducing ends.
D) The highly branched structure allows the rapid mobilization of glucose during metabolic need.
E) It is found primarily in the liver and skeletal muscles.

Question 37

Glucuronic acid is formed by oxidation of which carbon of glucose?

A) C-1
B) C-2
C) C-4
D) C-6
E) both a and b

Question 38

Cellulose is extremely resistant to hydrolysis, but cellulase catalyzes the hydrolysis and comes from:

A) the pancreas.
B) bacteria that live in the rumen.
C) the liver.
D) H⁺ secreted into the rumen.
E) the intestinal wall.

Question 39

Cooked starch is more digestible because:

A) it has been partially hydrolyzed during cooking.
B) the amylopectin is converted to amylose during cooking.
C) the enzymes that hydrolyze the starch are only active when the starch is hot.
D) the starch granules take up water, swell and are more accessible to the enzymes.
E) all are true.

Question 40

____ is an enzyme found in liver and muscle tissue used to catalyze the phosphorolysis of glycogen to ____.

A) β (1→6)-Glucosidase; glucose-1-phosphate
B) α-Amylase; glucose-1-phosphate
C) β-Amylase; glucose
D) Glycogen maltase; maltose
E) Glycogen phosphorylase; glucose-1-phosphate

Question 41

Discuss the structure of glycogen.​

Question 42

Glycosaminoglycans are unbranched polysaccharides consisting of alternating residues of uronic acid and hexosamine. Which of the following is NOT a glycosaminoglycan?

A) agaropectin
B) heparin
C) dermatan sulfate
D) hyaluronate
E) chondroitin-4-sulfate

Question 43

Which of the following statements is true regarding glycogen?

A) the branches are formed by α(2→6) glycosidic bonds
B) glycogen is the primary energy storage molecule for animals
C) most of the glycosidic bonds are α(1→4)
D) glycogen is considered a heteropolysaccharide
E) none of the above are true

Question 44

____ are important components of the vitreous humor of the eye and of synovial fluid that lubricates the joints.

A) Heparin
B) Hyaluronates
C) Chondroitins
D) Keratin sulfates
E) All are true

Question 45

Which of the following best describes the glycosidic bond below?

A) β(2→4)
B) α(1→3)
C) α(1→4)
D) β(1→3)
E) α(2→4)

Question 46

Cartilage-matrix proteoglycan has all of the following properties EXCEPT:

A) responsible for the flexibility and resiliency of cartilage.
B) has a hyaluronic acid binding domain.
C) has reversible hydration-dehydration properties.
D) contains both N-linked and O-linked oligosaccharides.
E) is an integral transmembrane protein.

Question 47

Briefly explain lectins with an example.​

Question 48

____ and ____ are found in tendons, cartilage and other connective tissue.

A) Heparin; chondroitins
B) Chondroitins; keratin sulfate
C) Keratin sulfate, dermatan sulfate
D) Hyaluronate, keratin sulfate
E) All are true.

Question 49

Which of the following represents an example of a proteoglycan?

A) attachment of several molecules of heparin to the peptide antithrombin III
B) attachment of a Gal-β(1,3)-GalNAc disaccharide to the fish antifreeze protein
C) attachment of a small oligosaccharide to an immunoglobulin
D) attachment of a small antigenic determinant to a membrane bound protein of a cell
E) none of the above

Question 50

Discuss the glycoproteins and glycolipids that have terminal sialic acids on their oligosaccharide chains.​

Question 51

Which of the following would be the correct Haworth projection for β-D-talose (linear form is shown on the left)?

A) a
B) b
C) c
D) d
E) none of the above

Question 52

Explain how proteoglycans make cartilage flexible and resilient.​

Question 53

Amylose and glycogen are both glucose polymers, yet they have somewhat different properties. What is one important difference between them?

A) One is made with D-glucose and the other with L-glucose
B) One is used as a structural polymer in insects; the other for energy in plants
C) One contains α glycosidic bonds while the other contains β glycosidic bonds
D) One is a linear polymer while the other is highly branched
E) none of the above explain the difference between amylose and glycogen

Question 54

All are true for agarose EXCEPT:

A) Forms a double helix with a central core large enough to accommodate large quantities of water.
B) Consists of only a linear component.
C) Is a chain of alternating D-galactose and 3,6-anhydro-L-galactose, with side-chains of 6-methyl-D-galactose.
D) Readily forms gels that are up to 99.9% water.
E) All are true.

Question 55

Which of the following monosaccharides is an aldose?

A) a
B) b
C) c
D) d
E) none of the above

Question 56

The core protein of a proteoglycan is noncovalently attached to:

A) oligosaccharides.
B) glycosaminoglycans.
C) keratin sulfate.
D) an outer protein.
E) hyaluronic acid backbone.

Question 57

Discuss anomers.​

Question 58

Proteoglycans are a group of macromolecules formed from:

A) proteases and monosaccharides.
B) proteins and glycosaminoglycans.
C) proteins and polysaccharides.
D) proteases and glycosaminoglycans.
E) proteins and glycogen.