Biochem Chapter 7

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

A

46. 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

A

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.

A

Which of the following sugars is an aldopentose? a. galactose b. ribulose c. ribose d. xylulose e. mannose

C. ribose

35. 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.

E

48. 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.

E

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

E

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.

E

30. In plant cells, starch is hydrolyzed by _________________ to release _________________ and a starch molecule with ________________.

a. starch phosphorylase; glucose-1-phosphate; one less glucose unit

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

aldehyde or ketone

27. Cellulose is a:

b. (1→4)-β-D-glucopyranan.

43. ____________ and _____________ are found in tendons, cartilage and other connective tissue.

b. Chondroitins; keratin sulfate

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

b. Hyaluronates

18. _____________ 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.

b. Muramic acid; neuraminic acid

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

b. bacteria that live in the rumen.

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

b. both anomeric carbons are involved in formation of the glycosidic bond

19. A glycosidic bond would be present in:

b. methyl-β-D-glucoside.

45. Proteoglycans are a group of macromolecules formed from:

b. proteins and glycosaminoglycans.

39. Cellulase is considered a ____________.

b. β-(1→4) glucosidase

16. Honey is characteristically composed predominantly of

c. fructose and glucose

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

c. numbers of molecules

26. _____________ 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.

d. Stachyose

28. Mucopolysaccharides such as ______________ form protective coats on animal cells.

d. hyaluronic acids

31. Cooked starch is more digestible because:

d. the starch granules take up water, swell and are more accessible to the enzymes.

32. Neither α-amylase or β-amylase can cleave the ___________ bonds of amylopectin and ____________ glucosidase is required to completely hydrolyze starch.

e. Glycogen phosphorylase; glucose-1-phosphate

33. _________________ is an enzyme found in liver and muscle tissue used to catalyze the hydrolysis of glycogen to ______________________.

e. Glycogen phosphorylase; glucose-1-phosphate

36. Which of the following statements about cellulose fiber is true?

e. Intermolecular hydrogen bonds play a major role in stabilization of the microfibrils.

47. The core protein of a proteoglycan is noncovalently attached to:

e. hyaluronic acid backbone.

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

elevated; glucose; reducing sugars

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

maltose

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

pyranose

A constituent of the flavin coenzymes is

ribitol

Xylulose is an epimer of:

ribulose

25. "Blood sugar" in hemolymph of insects is __________ represented as _____________.

trehalose; GlcααGlc

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

5

Draw beta-D-Galactosamine

...

Draw beta-D-Glucosamine

...

40. 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.

A

41. 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.

B

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.

C

21. All of the following disaccharides are reducing sugars EXCEPT: a. lactose. b. maltose. c. sucrose. d. cellulose. e. isomaltose.

C

34. 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.

C

37. 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.

C

All of the following statements about cyclic sugars are true EXCEPT: a. The α-anomer has the -OH of the anomeric carbon positioned on the opposite side of the sugar ring from the -CH2OH. b. The five and six membered rings are more frequently observed due to stability. c. In a chair conformation, the predominant form has the bulkiest substituents occupying axial positions. d. The carbonyl carbon becomes a chiral center. e. They can be formed by the intramolecular reactions to hemiacetals or hemiketals.

C

Sugar alcohols include all of the following EXCEPT: a. ribitol. b. sorbitol. c. fucose. d. mannitol. e. glycerol.

C

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

C-6

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.

D

The enantiomer of D-mannose would be:

L-mannose

Glucose most commonly forms which of the following structures?

a pyranose using the hydroxyl group on carbon 5

23. All of the following are homodisaccharides EXCEPT: a. lactose. b. maltose. c. isomaltose. d. cellobiose. e. all are homodisaccharides.

a. lactose.