Chapter 3: Proteins, Carbohydrates, and Lipids

8. Which of the following functional groups is the most polar? a. Hydroxyl b. Aldehyde c. Keto d. Carboxylic acids e. Sulfhydryl

a. Hydroxyl

66. Lipids form the barriers surrounding various compartments within an organism. Which property of lipids makes them a good barrier? a. Many biologically important molecules are not soluble in lipids. b. Lipids are polymers. c. Lipids store energy. d. Triglycerides are lipids. e. Lipids release large amounts of energy when broken down.

a. Many biologically important molecules are not soluble in lipids.

63. Which of the following statements about lipids is false? a. They are readily soluble in water. b. They help capture light energy. c. They release large amounts of energy when broken down. d. They form two layers when mixed with water. e. They act as an energy storehouse.

a. They are readily soluble in water.

33. Quaternary structure is found in proteins a. composed of subunits. b. of membranes. c. of the quadruple complex. d. that change over time. e. None of the above

a. composed of subunits.

47. Lactose, or milk sugar, which is composed of one glucose unit and one galactose unit, can be classified as a a. disaccharide. b. hexose. c. pentose. d. polysaccharide. e. monosaccharide.

a. disaccharide.

61. A fat contains fatty acids and a. glycerol. b. a base. c. an amino acid. d. a phosphate. e. None of the above

a. glycerol.

70. In a biological membrane, the phospholipids are arranged with the fatty acid chains facing the interior of the membrane. As a result, the interior of the membrane is a. hydrophobic. b. hydrophilic. c. charged. d. polar. e. filled with water.

a. hydrophobic.

31. The tertiary structure of a protein is determined by its a. interactions among R groups. b. right-handed coil. c. hydrogen bonding. d. branching. e. glycosidic linkages.

a. interactions among R groups.

50. Starch and glycogen, which are both polysaccharides, differ structurally in that glycogen _______, whereas starch _______. a. is highly branched; is moderately branched b. consists of parallel strands; is highly branched c. consists of a combination of branching and parallel strands; is moderately branched d. is moderately branched; consists of parallel strands e. is highly branched; consists of parallel strands

a. is highly branched; is moderately branched

42. Glucose and fructose both have the formula C6H12O6, but the atoms in these two compounds are arranged differently. Glucose and fructose are therefore a. isomers. b. polysaccharides. c. oligosaccharides. d. pentoses. e. steroids.

a. isomers.

69. Unsaturated fatty acids do not pack together due to a. kinks in the hydrocarbon-chain ribozymes. b. glycosidic linkage proteases. c. peptide-bond chaperonins. d. disulfide bridges. e. van der Waals-force triglycerides.

a. kinks in the hydrocarbon-chain ribozymes.

13. During the formation of a peptide linkage, a(n) _______ is formed. a. molecule of water b. disulfide bridge c. hydrophobic bond d. hydrophilic bond e. ionic bond

a. molecule of water

17. A protein can best be defined as a polymer a. of amino acids. b. containing one or more polypeptide chains. c. containing 20 amino acids. d. containing 20 peptide linkages. e. containing double helices.

a. of amino acids.

45. DNA and RNA both include a. pentoses. b. hexoses. c. fructoses. d. maltoses. e. amyloses.

a. pentoses.

9. An essential functional group involved in cellular energy transfer is the _______ group. a. phosphate b. amino c. sulfhydryl d. hydroxyl e. saccharide

a. phosphate

3. The compound inositol has six hydroxyl groups attached to a six-carbon backbone. Thus inositol can be classified as a(n ) _______.

alcohol

14. Glucosamine and galactosamine are monosaccharides in which a hydroxyl group has been replaced by a(n) _______ group.

amino

24. What type of amino acid side chains would you expect to find on the surface of a protein embedded in a cell membrane? a. Cysteine b. Hydrophobic c. Hydrophilic d. Charged e. Polar, but not charged

b. Hydrophobic

51. Why does a starchy food, like bread, become hard and stale when it dries out? a. Cellulose molecules aggregate in the absence of water. b. In the absence of water, unbranched starch forms hydrogen bonds between polysaccharides, which then aggregate. c. The release of carbon dioxide causes the bread to harden. d. Water and heat cause the polysaccharide chains to bind together. e. Mold growth interferes with α linkages, causing the bread to harden.

b. In the absence of water, unbranched starch forms hydrogen bonds between polysaccharides, which then aggregate.

64. You have isolated an unidentified liquid from a sample of beans. You add the liquid to a beaker of water and shake vigorously. After a few minutes, the water and the other liquid separate into two layers. To which class of large biological molecules does the unknown liquid most likely belong? a. Carbohydrates b. Lipids c. Proteins d. Enzymes e. Nucleic acids

b. Lipids

67. You look at the label on a container of shortening and see the words "hydrogenated vegetable oil." This means that during processing, the number of carbon-carbon double bonds in the oil was decreased. What is the result of decreasing the number of double bonds? a. The oil now has a lower melting point. b. The oil is now solid at room temperature. c. There are more "kinks" in the fatty acid chains. d. The oil is now a derivative carbohydrate. e. The fatty acid is now a triglyceride.

b. The oil is now solid at room temperature.

5. The amino and carboxyl functional groups tend to form bases and acids by attracting or dropping a. a neutron. b. a proton. c. an electron. d. a proton and an electron. e. a neutron and a proton.

b. a proton.

14. Polysaccharides, polypeptides, and polynucleotides a. contain simple sugars. b. are broken down in hydrolysis reactions. c. are found in cell membranes. d. contain nitrogen. e. have molecular weights less than 30,000 daltons.

b. are broken down in hydrolysis reactions.

60. Fatty acids are molecules that a. contain fats bonded to a glycerol. b. are composed of hydrogen, carbon, and a carboxyl group. c. are carbohydrates linked to a hydrocarbon chain. d. contain glycerol and a carboxyl group. e. are always saturated.

b. are composed of hydrogen, carbon, and a carboxyl group.

20. Leucine and valine do not interact with water; therefore, they a. are hydrophilic. b. are nonpolar. c. have sulfur atoms in their side chains. d. are electrically charged. e. form only left-hand isomers.

b. are nonpolar.

36. Knowledge that incorrect folding of a protein can be deleterious to cell functioning is being used to design drugs to treat a. rickets. b. cancerous tumors. c. hemophilia. d. diabetes. e. high blood pressure.

b. cancerous tumors.

38. A molecule with the formula C16H30O15 is a a. hydrocarbon. b. carbohydrate. c. lipid. d. protein. e. nucleic acid.

b. carbohydrate.

26. An amino acid that is small enough to fit into tight corners of protein molecules is a. proline. b. glycine. c. cysteine. d. asparagine. e. glutamine.

b. glycine.

68. The portion of a phospholipid that contains the phosphorous group has one or more electric charges. That makes this region of the molecule a. hydrophobic. b. hydrophilic. c. nonpolar. d. unsaturated. e. saturated.

b. hydrophilic.

41. The difference between α- and β-glucose is a. in the number of covalent bonds present. b. in the placement of OH and H atoms. c. in the type of R group attached to the terminal carbon. d. that α-glucose is polar, whereas β-glucose is nonpolar. e. that α-glucose is a pentose, whereas β-glucose is a hexose.

b. in the placement of OH and H atoms.

56. In animals, glucose is stored in the compound a. cellulose. b. amylose. c. glycogen. d. fructose. e. cellobiose.

c. glycogen.

21. Aspartate and glutamate are highly soluble in water; therefore, they a. are hydrophobic. b. have sulfur atoms in their side chains. c. have electrically charged side chains. d. are nonpolar. e. form only left-hand isomers.

c. have electrically charged side chains.

53. Starch and glycogen are different in that only one of them a. is a polymer of glucose. b. contains ribose. c. is made in plants. d. is an energy storage molecule. e. can be digested by humans.

c. is made in plants.

43. The monomers that make up polymeric carbohydrates like starch are called a. nucleotides. b. trisaccharides. c. monosaccharides. d. nucleosides. e. fatty acids.

c. monosaccharides

65. A molecule that has an important role in limiting what gets into and out of cells is a. glucose. b. maltose. c. phospholipid. d. fat. e. phosphohexose.

c. phospholipid.

52. Starch and glycogen, which are both polysaccharides, differ in their functions in that starch is _______, whereas glycogen _______. a. the main component for plant structural support; is an energy source for animals b. a structural material found in plants and animals; forms external skeletons in animals c. the principle energy storage compound of plants; is the main energy storage of animals d. a temporary compound used to store glucose; is a highly stable compound that stores complex lipids e. is the main energy storage of animals; a temporary compound used to store glucose

c. the principle energy storage compound of plants; is the main energy storage of animals

2. The functional group written as —COOH is called the _______ group.

carboxyl

5. All amino acids have a hydrogen atom, an amino group, and a _______ group.

carboxyl

4. The reaction H—A—OH + H—B—OH → H—A—B—OH + H2O represents a _______.

condensation reaction

15. Which of the following is responsible for making every amino acid unique? a. Amino group b. Hydrogen c. Carboxyl group d. "R" group e. Carbon

d. "R" group

22. The side chain of leucine is a hydrocarbon. In a folded protein, where would you expect to find leucine? a. In the interior of a cytoplasmic enzyme b. On the exterior of a protein embedded in a membrane c. On the exterior of a cytoplasmic enzyme d. Both a and b e. Both a and c

d. Both a and b

35. Which of the following protein structures is destroyed by denaturation? a. Primary b. Secondary c. Tertiary d. Both b and c e. All of the above

d. Both b and c

40. The atoms that make up carbohydrates are a. C, H, and N. b. C and H. c. C, H, and P. d. C, H, and O. e. C, H, O, and N.

d. C, H, and O.

19. Which of the following amino acids does not have an optical isomer? a. Arginine b. Cysteine c. Alanine d. Glycine e. Methionine

d. Glycine

18. Which of the following statements about proteins is true? a. They are insoluble in water. b. They are the structural units of glycogen. c. They possess glycosidic linkages between amino acids. d. Some function as enzymes. e. They are involved in information storage.

d. Some function as enzymes.

62. Which of the following is not a function in which lipids play an important role? a. Vision b. Storing energy c. Membrane structure d. Storing genetic information e. Chemical signaling

d. Storing genetic information

54. Two important polysaccharides made up of glucose monomers are _______ and _______. a. guanine; cytosine b. RNA; DNA c. sucrose; lactose d. cellulose; starch e. testosterone; cortisone

d. cellulose; starch

3. The bonds that form between the atoms of polymeric macromolecules are _______ bonds. a. hydrogen b. peptide c. disulfide d. covalent e. ionic

d. covalent

48. Maltose and lactose are similar in that they both are a. simple sugars. b. amino acids. c. insoluble in water. d. disaccharides. e. hexoses.

d. disaccharides.

1. Large molecules that contain carbon and are held together by covalent bonds are categorized as a. proteins. b. polymers. c. nucleic acids. d. macromolecules. e. monomers.

d. macromolecules.

44. A simple sugar with the formula C5H10O5 can be classified as a a. hexose. b. polysaccharide. c. disaccharide. d. pentose. e. lipid.

d. pentose.

16. Enzymes are a. DNA. b. lipids. c. carbohydrates. d. proteins. e. amino acids.

d. proteins.

10. Carbohydrates made up of two simple sugars are called _______.

disaccharides

9. The covalent bond formed between the sulfur atoms of two cysteine side chains is called a _______.

disulfide bridge

28. There are _______ different types of tripeptides (molecules with three amino acids linked together) that can exist using the 20 common amino acids. a. 3 b. 20 c. 60 d. 900 e. 8,000

e. 8,000

59. Lipids are a. insoluble in water. b. important for energy storage. c. hydrophobic. d. important constituents of biological membranes. e. All of the above

e. All of the above

72. Cholesterol is soluble in ether, an organic solvent, but it is not soluble in water. Based on this information, to which class of biological macromolecules does cholesterol belong? a. Nucleic acids b. Carbohydrates c. Proteins d. Enzymes e. Lipids

e. Lipids

2. Which of the following is not a macromolecule? a. RNA b. DNA c. Vitamin D, E, or K d. A protein e. Salt

e. Salt

8. Van der Waals forces can form between _______ side chains in proteins.

hydrophobic

18. Cholesterol is classified as a(n) _______.

lipid

19. Vitamins D, E, and F have a multiple-ring structure and are classified as _______.

lipids

17. The fluidity and melting point of fatty acids are partially determined by the number of _______ bonds.

unsaturated (or carbon double)

55. A molecule that has an important role in long-term storage of energy is a. a steroid. b. RNA. c. glycogen. d. an amino acid. e. hexose.

c. glycogen.

32. A β pleated sheet organization in a polypeptide chain is an example of _______ structure. a. primary b. secondary c. tertiary d. quaternary e. coiled

b. secondary

29. The shape of a folded protein is often determined by a. its tertiary structure. b. the sequence of its amino acids. c. whether the peptide bonds have α or β linkages. d. the number of peptide bonds. e. the base-pairing rules.

b. the sequence of its amino acids.

27. What is the theoretical number of different proteins that you could make from 50 amino acids? a. 50^20 b. 20 × 50 c. 20^50 d. 10^50 e. 2^50

c. 20^50

25. Peptide chains have a(n) _______ and a(n) _______ end. a. start; stop b. +; - c. N terminus; C terminus d. 5´; 3´ e. A; Z

c. N terminus; C terminus

4. Which of the following does not represent a correct monomer/polymer pairing? a. Monosaccharide/polysaccharide b. Amino acid/protein c. Triglyceride/cellulose d. Nucleotide/nucleic acid e. Monosaccharide/oligosaccharide

c. Triglyceride/cellulose

6. Aldehydes and ketones are very similar in that they both contain a. phosphorus atoms. b. sulfur atoms. c. a carbonyl group (C=O). d. nitrogen atoms. e. two "R" groups.

c. a carbonyl group (C=O).

71. Molecules that are both attracted to water and repel water are called a. hydrophilic. b. hydrophobic. c. amphipathic. d. amphoric. e. glycosidic.

c. amphipathic.

73. Steroids are classified as lipids because they a. have a ring structure similar to glucose. b. are composed of amino acids. c. are composed of nonpolar and hydrophobic molecules. d. are composed of molecules that are bound together with glycosidic linkages. e. form alpha and beta isomers.

c. are composed of nonpolar and hydrophobic molecules.

11. In condensation reactions, the atoms that make up a water molecule are derived from a. oxygen. b. only one of the reactants. c. both of the reactants. d. carbohydrates. e. enzymes.

c. both of the reactants.

37. A type of protein that functions by helping other proteins fold correctly is called a a. foldzyme. b. renaturing protein. c. chaperone protein. d. hemoglobin. e. denaturing protein.

c. chaperone protein.

74. Waxes are formed by a. adding water to fatty acids. b. removing water from fatty acids. c. combining fatty acids with alcohol. d. condensing fatty acids with glycerol. e. combining fatty acids with vitamin A.

c. combining fatty acids with alcohol.

34. A(n) _______ protein is a protein that has become nonfunctional due to the loss of its three-dimensional structure. a. permanent b. reversible c. denatured d. hydrolyzed e. environmentalized

c. denatured

49. Sucrose, known as common table sugar, is a a. hexose. b. lipid. c. disaccharide. d. glucose. e. simple sugar.

c. disaccharide.

58. Chitin is a polymer of a. galactosamine. b. glucose. c. glucosamine. d. glycine. e. All of the above

c. glucosamine.

46. A type of molecule very often drawn with a single six-sided ring structure is a. sucrose. b. an amino acid. c. glucose. d. a fatty acid. e. a steroid.

c. glucose.

10. Which of the following statements regarding the carbon atoms in a molecule and its functional groups is false? a. They determine how the molecule interacts with other molecules in the environment. b. They determine the shape of the molecule. c. They determine the specific properties of the molecule. d. They may have interactions with specific functional groups on the same molecule. e. They are antagonistic to each other, thereby creating multiple forces that drive chemical reactions.

e. They are antagonistic to each other, thereby creating multiple forces that drive chemical reactions.

23. Amino acids can be classified by the a. number of monosaccharides they contain. b. number of carbon-carbon double bonds in their fatty acids. c. number of peptide bonds they can form. d. number of disulfide bridges they can form. e. characteristics of their side chains, or "R" groups.

e. characteristics of their side chains, or "R" groups.

7. Molecules containing a large number of hydroxyl groups are a. basic. b. highly stable structurally. c. involved in reactions forming more complex molecules. d. nonpolar. e. highly soluble in water.

e. highly soluble in water.

30. The amino acids of the protein keratin are arranged in a helix. This secondary structure is stabilized by a. covalent bonds. b. peptide bonds. c. glycosidic linkages. d. polar bonds. e. hydrogen bonds.

e. hydrogen bonds.

12. Polymerization reactions in which polysaccharides are synthesized from monosaccharides a. require the formation of phosphodiester bonds between the amino acids. b. occur in the nucleus of the cell. c. are hydrolysis reactions. d. depend upon van der Waals forces to hold the amino acids together. e. result in the formation of water.

e. result in the formation of water.

57. The main function of cellulose, the most abundant organic compound on Earth, is a. to store genetic information. b. as a storage compound for energy in plant cells. c. as a storage compound for energy in animal cells. d. as a component of biological membranes. e. to provide mechanical strength to plant cell walls.

e. to provide mechanical strength to plant cell walls.

15. A(n) _______ linkage connects the fatty acid molecule to glycerol.

ester

11. All living cells contain the monosaccharide _______.

glucose

13. The highly branched polysaccharide that stores glucose in the muscles and the liver of animals is _______.

glycogen

12. The bonds that link sugar monomers in a starch molecule are _______ bonds.

glycosidic

1. Starch is a polymer of glucose subunits. The subunits of any polymer are called _______.

monomers

6. In proteins, amino acids are linked together by _______ bonds.

peptide

16. Fatty acids with more than one carbon-carbon double bond are called _______.

polyunsaturated

7. The linear arrangement of amino acids in the polypeptide chain is referred to as the _______ structure of the protein.

primary