Chapter 25 Amino Acids, Peptides, And Proteins Test Bank

Organic Chemistry, 4e (Klein)

Chapter 25 Amino Acids, Peptides, and Proteins

1) In α-amino acids, the amino and carboxylic acid groups are separated by ________.

A) two carbon atoms

B) one carbon atom

C) peptide linkage

D) amide linkage

E) none of these

Diff: 1

Learning Objective: 25.1 Describe the structures of amino acids, alpha amino acids, peptide bonds, peptides, and proteins

2) Which one or more of the given statements is true about α-amino acids?

A) the amino and carboxylic acid groups are separated by one carbon atom

B) the amino group is connected to a carbon atom that is α to the carboxylic acid group

C) the α carbon can be a chirality center

D) all of these are true

Diff: 1

Learning Objective: 25.1 Describe the structures of amino acids, alpha amino acids, peptide bonds, peptides, and proteins

3) Pairs of amino acids are connected together by ________.

A) an ether linkage

B) a peptide linkage

C) an ester linkage

D) an amide linkage

E) both B and D

Diff: 1

Learning Objective: 25.1 Describe the structures of amino acids, alpha amino acids, peptide bonds, peptides, and proteins

4) When four amino acids are connected to each other, they form ________.

A) a tripeptide

B) a protein

C) a polypeptide

D) a tetrapeptide

E) a dipeptide

Diff: 1

Learning Objective: 25.1 Describe the structures of amino acids, alpha amino acids, peptide bonds, peptides, and proteins

5) When two amino acids are connected to each other, they form ________.

A) a tripeptide

B) a protein

C) a polypeptide

D) a tetrapeptide

E) a dipeptide

Diff: 1

Learning Objective: 25.1 Describe the structures of amino acids, alpha amino acids, peptide bonds, peptides, and proteins

6) When three amino acids are connected to each other, they form ________.

A) a tripeptide

B) a protein

C) a polypeptide

D) a tetrapeptide

E) a dipeptide

Diff: 1

Learning Objective: 25.1 Describe the structures of amino acids, alpha amino acids, peptide bonds, peptides, and proteins

7) When thirty amino acids are connected to each other, they form ________.

A) a tripeptide

B) a protein

C) a polypeptide

D) a tetrapeptide

E) none of these

Diff: 1

Learning Objective: 25.1 Describe the structures of amino acids, alpha amino acids, peptide bonds, peptides, and proteins

8) When more than fifty amino acids are connected to each other, they form ________.

A) a tripeptide

B) a protein

C) a polypeptide

D) a tetrapeptide

E) none of these

Diff: 1

Learning Objective: 25.1 Describe the structures of amino acids, alpha amino acids, peptide bonds, peptides, and proteins

9) ________ are certain proteins that serve as catalysts for most of the reactions in living cells.

Diff: 1

Learning Objective: 25.1 Describe the structures of amino acids, alpha amino acids, peptide bonds, peptides, and proteins

10) How many different amino acids are abundantly found in proteins?

A) 10

B) 16

C) 20

D) 40

E) none of these

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

11) Proteins found in humans have all amino acids with ________ configuration.

A) D

B) L

C) meso

D) A and B

E) none of these

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

12) Which of the given amino acids is achiral?

A) alanine

B) leucine

C) glycine

D) phenylalanine

E) none of these

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

13) Which of the choices is a correct structure for L-valine?

A) I

B) II

C) III

D) IV

E) V

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

14) Which of the choices is a correct structure for D-leucine?

A) I

B) II

C) III

D) IV

E) V

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

15) Which one or more of the amino acids shown has have a basic side chain?

A) I and II

B) I, II and IV

C) III and V

D) I, II, III and IV

E) all of these

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

16) Which of the amino acids shown have an acidic side chain?

A) I and III

B) I, II and III

C) IV and V

D) II, IV and V

E) all of these

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

17) Which one of the given amino acids has a hydroxyl side chain?

A) cysteine

B) serine

C) glutamine

D) leucine

E) proline

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

18) Which one of the given amino acids has a sulfur atom?

A) cysteine

B) serine

C) glutamine

D) leucine

E) proline

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

19) Which one of the given amino acids has an amide side chain?

A) cysteine

B) serine

C) glutamine

D) leucine

E) proline

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

20) Which of the given amino acids has a polar side chain?

A) tyrosine

B) proline

C) leucine

D) tryptophan

E) glycine

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

21) Which of the given amino acids is the smallest?

A) tyrosine

B) proline

C) leucine

D) tryptophan

E) glycine

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

22) Which of the given amino acids is the largest amino acid with a nonpolar side chain?

A) tyrosine

B) proline

C) leucine

D) tryptophan

E) glycine

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

23) Which one of the given amino acid does not have an L-isomer?

A) valine

B) alanine

C) leucine

D) glycine

E) none of these

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

24) Which of the naturally occurring amino acids shown does not have the S configuration?

A) I

B) II

C) III

D) IV

E) none of these

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

25) Which of the given amino acids is not an essential amino acid?

A) phenylalanine

B) glycine

C) isoleucine

D) threonine

E) valine

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

26) Which choice shows the Fischer projection for D-serine with the chirality center correctly identified as R or S?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

27) Which choice shows the Fischer projection for L-cysteine with the chirality center correctly identified as R or S?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

28) Which choice shows the Fischer projection for L-aspartic acid with the chirality center correctly identified as R or S?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

29) An amino acid can exist as a ________, which is a dipolar ion that carries both positive and negative charge.

A) cation

B) anion

C) zwitterion

D) none of these

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

30) Amino acids are considered amphoteric because ________.

A) they only react with acids

B) they only react with bases

C) they react with both acids and bases

D) they do not react with acids or bases

E) none of these

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

31) Which of the choices is a zwitterion for alanine?

A) I

B) II

C) III

D) IV

E) both I and IV

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

32) Which of the choices is the predominant form of lysine at pH 14?

A) I

B) II

C) III

D) IV

E) V

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

33) Which of the choices is the predominant form of aspartic acid at pH 1?

A) I

B) II

C) III

D) IV

E) V

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

34) Which of the choices is the predominant form of serine at physiological pH?

A) I

B) II

C) III

D) IV

E) V

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

35) Which of the choices is the predominant form of asparagine at physiological pH?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

36) Which of the choices is the predominant form of arginine at pH 2?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

37) What is the structure of the predominant form of alanine at a pH of 2?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

38) What is the structure of the predominant form of valine at pH 10?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

39) Which of the given statements is true about the amino acids with isoelectric point around pH 10?

A) The side chain must be acidic.

B) The side chain must be basic.

C) The side chain must be polar.

D) The side chain must be non polar.

E) none of these

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

40) Which of the given statements is true about the amino acids with isoelectric point around pH 3?

A) The side chain must be acidic.

B) The side chain must be basic.

C) The side chain must be polar.

D) The side chain must be non polar.

E) none of these

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

41) The pH at which the concentration of the zwitterionic form of an amino acid is at a maximum value is called the ________.

A) dipolar point

B) electric point

C) neutral point

D) isoelectric point

E) none of these

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

42) What is the pI of the amino acid shown?

A) 2.76

B) 5.74

C) 6.62

D) 7.50

E) none of these

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

43) What is the pI of the amino acid shown?

A) 5.56

B) 6.35

C) 9.74

D) 10.53

E) none of these

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

44) What is the pI of the amino acid shown?

A) 1.16

B) 4.81

C) 5.97

D) 9.62

E) none of these

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

45) Which of the amino acids shown has a pI around pH 10?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

46) Which of the amino acids shown has a pI around pH 3?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

47) Which of the choices is used to detect the presence of amino acids using chromatography?

A) 2,4-DNP

B) methyl orange

C) phenolphthalein

D) ninhydrin

E) methyl red

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

48) Identify the compound that reacts with amino acids to form a fluorescent purple product.

A) 2,4-DNP

B) ninhydrin

C) methyl orange

D) methyl red

E) phenolphthalein

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

49) Separation of amino acids using electrophoresis is mainly based on ________.

A) differences in the pI values

B) concentration

C) differences in pH values

D) none of these

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

50) Which of the given amino acids will migrate towards the cathode at pH 7?

Glycine: pI = 6.0

Lysine: pI = 9.7

A) Glycine

B) Lysine

C) Both glycine and lysine

D) Neither glycine nor lysine

E) It is impossible to determine without more information.

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

51) Which of the given amino acids will migrate towards the anode at pH 7?

Glycine: pI = 6.0

Lysine: pI = 9.7

A) Glycine

B) Lysine

C) Both glycine and lysine

D) Neither glycine nor lysine

E) It is impossible to determine without more information.

Diff: 1

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

52) Which of the given amino acids will migrate towards the anode at pH 6?

Phenylalanine: pI = 5.5

Leucine: pI = 6

A) Phenylalanine

B) Leucine

C) Both phenylalanine and leucine

D) Neither phenylalanine nor leucine

E) It is impossible to determine without more information.

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

53) Which of the given amino acids will not migrate towards the cathode/anode at pH 6?

Phenylalanine: pI = 5.5

Leucine: pI = 6

A) Phenylalanine

B) Leucine

C) Both phenylalanine and leucine

D) Neither phenylalanine nor leucine

E) It is impossible to determine without more information.

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

54) Which of the given amino acids will move the farthest when subjected to electrophoresis at pH 7?

A) I

B) II

C) III

D) II and III

E) none of these

Diff: 2

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

55) Which choice indicates the structure of the predominant form of each of the given amino acids at pH 6 and correctly predicts whether it will migrate toward the anode or cathode during electrophoresis?

A) Phenylalanine is I and will move toward the anode; leucine is II and will move toward the cathode.

B) Phenylalanine is III and will move toward the anode; leucine is II and does not migrate.

C) Phenylalnine is V and will not move; leucine is IV and will move toward the cathode.

D) Phenylalnine is I and will not move; leucine is II and will move toward the cathode.

E) Phenylalanine is III and will move toward the cathode; leucine is II and does not migrate.

Diff: 3

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

56) Which choice shows the structure of the predominant form of each of the given amino acids at pH 7 and correctly predicts it will migrate toward the anode or cathode during electrophoresis?

A) Glycine is I and will move toward the anode; lysine is II and will move toward the cathode.

B) Glycine is III and will move toward the anode; lysine is II and does not migrate.

C) Glycine is V and will not move; lysine is IV and will move toward the cathode.

D) Glycine is I and will not move; lysine is II and will move toward the cathode.

E) Glycine is III and will move toward the cathode; lysine is II and does not migrate.

Diff: 3

Learning Objective: 25.2 Discuss the acid-base properties of amino acids, including pKa values, zwitterions, the amphoteric nature of amino acids, and the isoelectric point

57) Which amino acid is produced from the reaction sequence shown?

A) alanine

B) valine

C) leucine

D) isoleucine

E) none of these

Diff: 2

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

58) Which amino acid is produced from the reaction sequence shown?

A) alanine

B) valine

C) leucine

D) isoleucine

E) none of these

Diff: 2

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

59) Which amino acid is produced from the reaction sequence shown?

A) alanine

B) valine

C) leucine

D) isoleucine

E) none of these

Diff: 2

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

60) Which amino acid is produced from the reaction sequence shown?

A) alanine

B) valine

C) leucine

D) isoleucine

E) none of these

Diff: 2

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

61) How can you prepare phenylalanine using a Hell-Volhard-Zelinski reaction starting with the compound shown below?

A) 1. HBr; 2. H2O; 3. excess NH3

B) 1. Na2Cr2O7/H2SO4/H2O; 2. Br2/PBr3; 3. H2O; 4. excess NH3

C) 1. Na2Cr2O7/H2SO4/H2O; 2. HBr; 3. excess NH3

D) 1. Br2/PBr3; 2. H2O; 3. excess NH3

E) 1. Na2Cr2O7/H2SO4/H2O; 2. NaOH; 3. excess NH3

Diff: 3

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

62) How can you prepare glycine staring with ethanol and using a Hell-Volhard-Zelinski reaction?

A) 1. HBr; 2. H2O; 3. excess NH3

B) 1. Na2Cr2O7/H2SO4/H2O; 2. Br2/PBr3; 3. H2O; 4. excess NH3

C) 1. Na2Cr2O7/H2SO4/H2O; 2. HBr; 3. excess NH3

D) 1. Br2/PBr3; 2. H2O; 3. excess NH3

E) 1. Na2Cr2O7/H2SO4/H2O; 2. NaOH; 3. excess NH3

Diff: 3

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

63) In the Hell-Volhard-Zelinski reaction, the ________- carbon of the carboxylic acid is halogenated.

A) alpha

B) beta

C) gamma

D) delta

E) epsilon

Diff: 1

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

64) Which amino acid is produced from the reaction sequence shown?

A) alanine

B) valine

C) leucine

D) isoleucine

E) none of these

Diff: 3

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

65) Which amino acid is produced from the reaction sequence shown?

A) alanine

B) valine

C) leucine

D) isoleucine

E) none of these

Diff: 3

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

66) What is the structure of the amino acid produced from the reaction sequence shown?

A) I

B) II

C) III

D) IV

E) V

Diff: 3

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

67) What is the structure of the amino acid produced from the reaction sequence shown?

A) I

B) II

C) III

D) IV

E) V

Diff: 3

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

68) What reagents are necessary to synthesize the given amino acid via the amidomalonate synthesis?

Amidomalonate:

A) 1. NaOEt; 2. CH3CH2CH2Br; 3. H3O+

B) 1. NH4Cl/NaCN; 2. H3O+

C) 1. Br2/PBr3; 2. H2O; 3. excess NH3

D) 1. HBr; 2. H2O; 3. excess NH3

E) 1. NaOEt; 2. (CH3)2CHCH2Br; 3. H3O+/heat

Diff: 3

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

69) What reagents are necessary to synthesize the given amino acid via the amidomalonate synthesis starting with the given compound?

Amidomalonate:

A) 1. NaOEt; 2. ; 3. H3O+

B) 1. NH4Cl/NaCN; 2. H3O+

C) 1. Br2/PBr3; 2. H2O; 3. excess NH3

D) 1. HBr; 2. ; 3. H2O; 4. excess NH3

E) 1. NaOEt; 2. ; 3. H3O+/heat

Diff: 3

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

70) Which of the given aldehydes would produce isoleucine using a Strecker synthesis?

A) 3-methylbutanal

B) 2-methylbutanal

C) 2-methylpropanal

D) propanal

E) none of these

Diff: 2

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

71) Which of the given aldehydes would produce glycine using a Strecker synthesis?

A) methanal

B) ethanal

C) propanal

D) butanal

Diff: 2

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

72) Which amino acid is produced from the reaction shown?

A) methionine

B) serine

C) cysteine

D) lysine

E) none of these

Diff: 2

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

73) Which amino acid is produced from the reaction shown?

A) methionine

B) serine

C) cysteine

D) lysine

E) none of these

Diff: 2

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

74) Which choice shows how to prepare phenylalanine using a Strecker synthesis?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

75) Which choice shows how to prepare cysteine using a Strecker synthesis?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

76) What is the structure of the amino acid produced from the reaction shown?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

77) What is the structure of the amino acid produced from the reaction shown?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

78) Which of the given alkenes is used to prepare isoleucine using an asymmetric catalytic hydrogenation reaction?

A) I

B) II

C) III

D) IV

E) none of these

Diff: 3

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

79) What is the structure of the amino acid produced from the reaction sequence shown?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.3 Identify the reagents necessary to prepare amino acids, either as a racemic mixture or enantioselectively

80) Which of the choices is a correct bond-line structure for the tripeptide Val-Asp-Ala?

A) I

B) II

C) III

D) IV

E) none of these

Diff: 2

Learning Objective: 25.4 Describe the composition and structure of a peptide, including the N and C termini, s-trans and s-cis conformations, and disulfide bridges

81) Which of the choices is a correct bond-line structure for the tripeptide Ser-Lys-Cys?

A) I

B) II

C) III

D) IV

E) none of these

Diff: 2

Learning Objective: 25.4 Describe the composition and structure of a peptide, including the N and C termini, s-trans and s-cis conformations, and disulfide bridges

82) Which choices shows an accurate bond-line structure for the tetrapeptide Ala-Ser-Cys-Phe?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.4 Describe the composition and structure of a peptide, including the N and C termini, s-trans and s-cis conformations, and disulfide bridges

83) Which choice shows an accurate bond-line structure for the tetrapeptide Ile-Ser-Leu-Gly?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.4 Describe the composition and structure of a peptide, including the N and C termini, s-trans and s-cis conformations, and disulfide bridges

84) What is the correct sequence of amino acids for the given tripeptide?

A) Ser-Met-Ile

B) Ser-Cys-Ile

C) Thr-Met-Leu

D) Thr-Cys-Leu

E) Ile-Met-Thr

Diff: 2

Learning Objective: 25.4 Describe the composition and structure of a peptide, including the N and C termini, s-trans and s-cis conformations, and disulfide bridges

85) What is the correct sequence of amino acids for the given tripeptide?

A) Leu-Phe-Ala

B) Val-Phe-Ala

C) Ile-Tyr-Leu

D) Leu-Tyr-Val

E) Val-Ala-Phe

Diff: 2

Learning Objective: 25.4 Describe the composition and structure of a peptide, including the N and C termini, s-trans and s-cis conformations, and disulfide bridges

86) What is the three letter abbreviation for the amino acid sequence of the given peptide?

A) Ile-Phe-Ser-Val-Ala-Tyr

B) Phe-Ala-Val-Ser-Tyr-Ile

C) Gly-Phe-Val-Ser-Ala-Tyr

D) Ile-Tyr-Ser-Val-Ala-Phe

E) Leu-Ala-Ser-Tyr-Gly-Ala

Diff: 2

Learning Objective: 25.4 Describe the composition and structure of a peptide, including the N and C termini, s-trans and s-cis conformations, and disulfide bridges

87) Why is the s-trans conformation of a peptide bond more stable than the s-cis conformation?

A) there is a restricted rotation around the peptide bond

B) rotation is allowed around the peptide bond

C) it has reduced steric hindrance

D) none of these

Diff: 1

Learning Objective: 25.4 Describe the composition and structure of a peptide, including the N and C termini, s-trans and s-cis conformations, and disulfide bridges

88) How are disulfide bonds formed?

A) oxidation of thiol groups

B) joining cysteine residues within a peptide

C) joining cysteine residues between two strands of a peptide

D) all of these

Diff: 1

Learning Objective: 25.4 Describe the composition and structure of a peptide, including the N and C termini, s-trans and s-cis conformations, and disulfide bridges

89) Which of the given reagents is used to remove the N-terminus amino acid residue using Edman degradation?

A) I

B) II

C) III

D) IV

E) none of these

Diff: 2

Learning Objective: 25.5 Explain how the amino acid sequence of a peptide can determined via an Edman degradation or the use of peptidases

90) Edman degradation removes one amino acid residue at a time from the ________ of the peptide.

A) C-terminus

B) N-terminus

C) middle

D) none of these

Diff: 1

Learning Objective: 25.5 Explain how the amino acid sequence of a peptide can determined via an Edman degradation or the use of peptidases

91) Which of the given peptides results after a single Edman degradation of the tetrapeptide Gly-Phe-Tyr-Ser?

A) Gly-Phe-Tyr

B) Tyr-Ser

C) Phe-Tyr-Ser

D) Gly-Phe

E) Ser

Diff: 2

Learning Objective: 25.5 Explain how the amino acid sequence of a peptide can determined via an Edman degradation or the use of peptidases

92) Which of the given choices results after three steps of Edman degradation of the heptapeptide Lys-His-Gly-Phe-Tyr-Ser-Ala?

A) Lys-His-Gly

B) Phe-Tyr-Ser-Ala

C) Tyr-Ser-Ala

D) Lys-His-Gly-Phe

E) Gly-Phe-Tyr-Ser-Ala

Diff: 2

Learning Objective: 25.5 Explain how the amino acid sequence of a peptide can determined via an Edman degradation or the use of peptidases

93) Chymotrypsin, a digestive enzyme, catalyzes the hydrolysis of the peptide bond at the carboxyl end of which of the given amino acids?

A) phenylalanine

B) tyrosine

C) tryptophan

D) histidine

E) A, B and C

Diff: 2

Learning Objective: 25.5 Explain how the amino acid sequence of a peptide can determined via an Edman degradation or the use of peptidases

94) Trypsin, a digestive enzyme, catalyzes the hydrolysis of the peptide bond at the carboxyl end of which of the given amino acids?

A) arginine

B) lysine

C) histidine

D) tryptophan

E) A and B

Diff: 2

Learning Objective: 25.5 Explain how the amino acid sequence of a peptide can determined via an Edman degradation or the use of peptidases

95) Which of the given tetrapeptides is not cleaved by trypsin?

A) Gly-Lys-Cys-Phe

B) Cys-Ala-Arg-Ser

C) Gly-Ser-Ile-Lys

D) Ala-Lys-Tyr-Arg

E) Lys-Met-Pro-Ala

Diff: 2

Learning Objective: 25.5 Explain how the amino acid sequence of a peptide can determined via an Edman degradation or the use of peptidases

96) Which of the given tetrapeptides is not cleaved by chymotrypsin?

A) Gly-Lys-Cys-Trp

B) Cys-Tyr-Arg-Phe

C) Phe-Ser-Ile-Lys

D) Ala-Trp-Tyr-Arg

E) Phe-Met-Pro-Arg

Diff: 2

Learning Objective: 25.5 Explain how the amino acid sequence of a peptide can determined via an Edman degradation or the use of peptidases

97) Which of the given fragments are formed when the peptide shown is cleaved using chymotrypsin?

Gly-Lys-Cys-Phe-Ile-Val-Tyr-Ala-Ser

A) Gly-Lys-Cys, Phe-Ile-Val, Tyr-Ala-Ser

B) Gly-Lys-Cys-Phe, Ile-Val-Tyr, Ala-Ser

C) Gly-Lys-Cys-Phe, Ile-Val, Tyr-Ala-Ser

D) Gly-Lys-Cys, Phe, Ile-Val-Tyr, Ala-Ser

E) Gly-Lys, Cys-Phe, Ile-Val-Tyr-Ala-Ser

Diff: 2

Learning Objective: 25.5 Explain how the amino acid sequence of a peptide can determined via an Edman degradation or the use of peptidases

98) Which of the given sets of fragments is formed when the given peptide is cleaved using trypsin?

Gly-Lys-Cys-Phe-Ile-Val-Tyr-Ala-Ser

A) Gly, Lys-Cys, Phe-Ile-Val, Tyr-Ala-Ser

B) Gly-Lys, Cys-Phe-Ile-Val-Tyr-Ala-Ser

C) Gly-Lys-Cys-Phe, Ile-Val-Tyr-Ala-Ser

D) Gly-Lys, Cys, Phe-Ile-Val, Tyr-Ala-Ser

E) Gly-Lys-Cys-Phe, Ile-Val, Tyr-Ala-Ser

Diff: 2

Learning Objective: 25.5 Explain how the amino acid sequence of a peptide can determined via an Edman degradation or the use of peptidases

99) A peptide with 12 amino acid residues produced the given fragments when treated with trypsin and chymotrypsin. Edman degradation of this peptide produced the phenylthiohydantoin derivative of glycine. What is the structure of this peptide?

Trypsin: Gly-Leu-Phe-Arg, Cys-Tyr-Ile-Gly, Val-Trp-Ser-Lys

Chymotrypsin: Gly-Leu-Phe, Ser-Lys-Cys-Tyr, Ile-Gly, Arg-Val-Trp

A) Gly-Leu-Phe-Arg-Val-Trp-Ser-Lys-Cys-Tyr-Ile-Gly

B) Gly-Leu-Phe-Arg-Cys-Tyr-Ile-Gly-Val-Trp-Ser-Lys

C) Gly-Leu-Phe-Val-Trp-Ser-Lys-Cys-Tyr-Ile-Gly

D) Val-Trp-Ser-Lys-Gly-Leu-Phe-Arg-Cys-Tyr-Ile-Gly

E) Ser-Lys-Cys-Tyr-Gly-Leu-Phe-Arg-Val-Trp-Ile-Gly

Diff: 3

Learning Objective: 25.5 Explain how the amino acid sequence of a peptide can determined via an Edman degradation or the use of peptidases

100) Which of the given reagents is used to protect the amino group in the selective synthesis of the dipeptide Ala-Val?

A) I

B) II

C) III

D) IV

E) V

Diff: 2

Learning Objective: 25.6 Describe the reagents and reaction sequence necessary for peptide synthesis, including the Merrifield synthesis

101) Which of the given dipeptides is formed when alanine and valine are reacted in the presence of dicyclohexylcarbodiimide (DCC)?

A) Ala-Val

B) Val-Ala

C) Ala-Ala

D) Val-Val

E) all of these

Diff: 3

Learning Objective: 25.6 Describe the reagents and reaction sequence necessary for peptide synthesis, including the Merrifield synthesis

102) Which of the given dipeptides is formed when leucine is treated with (BoC)2O and glycine is treated with benzyl alcohol/acid first and the resulting intermediates are reacted in the presence of DCC followed by treatment with trifluoroacetic acid and then aqueous NaOH?

A) Gly-Leu

B) Gly-Gly

C) Leu-Gly

D) Leu-Leu

E) all of these

Diff: 3

Learning Objective: 25.6 Describe the reagents and reaction sequence necessary for peptide synthesis, including the Merrifield synthesis

103) Which of the given dipeptides is formed when tyrosine is treated with (BoC)2O and proline is treated with benzyl alcohol/acid first and the resulting intermediates are reacted in the presence of DCC followed by treatment with trifluoroacetic acid and then aqueous NaOH?

A) Tyr-Pro

B) Pro-Tyr

C) Pro-Pro

D) Tyr-Tyr

E) all of these

Diff: 3

Learning Objective: 25.6 Describe the reagents and reaction sequence necessary for peptide synthesis, including the Merrifield synthesis

104) Which of the given tripeptides is formed when alanine is treated with (BoC)2O and proline is treated with benzyl alcohol/acid first and the resulting intermediates are reacted in the presence of DCC followed by treatment with aqueous NaOH. The dipeptide is then reacted with the benzyl ester of leucine in the presence of DCC followed by treatment with trifluoroacetic acid and then aqueous NaOH?

A) Ala-Pro-Leu

B) Pro-Ala-Leu

C) Leu-Ala-Pro

D) Pro-Leu-Ala

E) all of these

Diff: 3

Learning Objective: 25.6 Describe the reagents and reaction sequence necessary for peptide synthesis, including the Merrifield synthesis

105) Which of the given tripeptides is formed when serine is treated with (BoC)2O and threonine is treated with benzyl alcohol/acid first and the resulting intermediates are reacted in the presence of DCC followed by treatment with aqueous NaOH. The dipeptide is then reacted with the benzyl ester of isoleucine in the presence of DCC followed by treatment with trifluoroacetic acid and then aqueous NaOH?

A) Ser-Tyr-Ile

B) Ser-Thr-Ile

C) Ile-Ser-Thr

D) Ile-Ser-Tyr

E) none of these

Diff: 3

Learning Objective: 25.6 Describe the reagents and reaction sequence necessary for peptide synthesis, including the Merrifield synthesis

106) Provide a stepwise synthesis for the dipeptide Ser-Phe beginning by adding the products of the two steps shown.

A) 1. DCC; 2. H2SO4; 3. NaOH/H2O

B) 1. Br2/PBr3; 2. H2O; 3. excess NH3

C) 1. NaOEt; 2. CH3Br; 3. H3O+, heat

D) 1. DCC; 2. NaOH/H2O; 3. excess NH3

E) 1. DCC; 2. CF3COOH; 3. NaOH/H2O

Diff: 3

Learning Objective: 25.6 Describe the reagents and reaction sequence necessary for peptide synthesis, including the Merrifield synthesis

107) The method developed by ________ is used to prepare larger peptides.

A) Edman

B) Strecker

C) Merrifield

D) Hell-Volhardt-Zelinski

Diff: 1

Learning Objective: 25.6 Describe the reagents and reaction sequence necessary for peptide synthesis, including the Merrifield synthesis

108) Which of the given choices is the correct sequence of the tetrapeptide that is formed by the reaction sequence shown?

A) Cys-Ala-Phe-Ser

B) Cys-Phe-Ala-Ser

C) Ser-Ala-Phe-Cys

D) Ser-Phe-Ala-Cys

E) none of these

Diff: 3

Learning Objective: 25.6 Describe the reagents and reaction sequence necessary for peptide synthesis, including the Merrifield synthesis

109) Provide the steps necessary to prepare the tetrapeptide Thr-Val-Ile-Met using the Merrifield synthesis beginning with a polymer bonded to CH2Cl.

A) Sequence 1

B) Sequence 2

C) Sequence 3

D) Sequence 4

E) Sequence 5

Diff: 3

Learning Objective: 25.6 Describe the reagents and reaction sequence necessary for peptide synthesis, including the Merrifield synthesis

110) Which of the given choices is the correct sequence for the pentapeptide that is formed by the reaction sequence shown?

A) Leu-Lys-Ala-Gly-Met

B) Met-Gly-Ala-Lys-Leu

C) Cys- Gly-Ala-Lys-Leu

D) Leu-Lys-Ala-Gly-Cys

E) none of these

Diff: 3

Learning Objective: 25.6 Describe the reagents and reaction sequence necessary for peptide synthesis, including the Merrifield synthesis

111) Which of the given choices is the correct sequence for the pentapeptide that is formed by the reaction sequence shown?

A) Ser-Thr-Pro-Lys-Leu

B) Leu-Lys-Pro-Thr-Ser

C) Thr-Thr- Pro-Lys-Leu

D) Leu-Lys-Pro-Thr-Thr

E) none of these

Diff: 3

Learning Objective: 25.6 Describe the reagents and reaction sequence necessary for peptide synthesis, including the Merrifield synthesis

112) The ________ of amino acids in a protein is referred to as its primary structure.

A) twisting

B) sequence

C) folding

D) bonding

E) reacting

Diff: 1

Learning Objective: 25.7 Describe the primary, secondary, tertiary, and quaternary structures of proteins, and the structures of the alpha helix and beta pleated sheet

113) The ________ structure of a protein is most important because the ________ of the amino acids determines its overall shape, function and properties.

A) primary; twisting

B) primary; sequence

C) secondary; twisting

D) secondary; folding

E) tertiary; folding

Diff: 1

Learning Objective: 25.7 Describe the primary, secondary, tertiary, and quaternary structures of proteins, and the structures of the alpha helix and beta pleated sheet

114) The secondary structure of a protein is due to ________ between amino acid residues.

A) hydrophobic interactions

B) hydrogen bonding

C) salt bridges

D) disulfide linkage

E) covalent bonding

Diff: 1

Learning Objective: 25.7 Describe the primary, secondary, tertiary, and quaternary structures of proteins, and the structures of the alpha helix and beta pleated sheet

115) The hydrogen bonding between the carbonyl group of an amino acid with the amino group of the fourth amino acid farther along the chain leads to ________.

A) parallel β-pleated sheets

B) antiparallel β-pleated sheets

C) α-helix

D) β-helix

E) none of these

Diff: 1

Learning Objective: 25.7 Describe the primary, secondary, tertiary, and quaternary structures of proteins, and the structures of the alpha helix and beta pleated sheet

116) Hydrogen bonding between the carbonyl group of an amino acid on one strand with the amino group of the neighboring strand leads to ________.

A) parallel β-pleated sheets

B) antiparallel β-pleated sheets

C) an α-helix

D) a β-helix

E) either A or B

Diff: 1

Learning Objective: 25.7 Describe the primary, secondary, tertiary, and quaternary structures of proteins, and the structures of the alpha helix and beta pleated sheet

117) Which of the choices is a secondary structure of fibroin found in spider web and silk?

A) β-pleated sheets

B) α-pleated sheets

C) α-helix

D) β-helix

E) none of these

Diff: 1

Learning Objective: 25.7 Describe the primary, secondary, tertiary, and quaternary structures of proteins, and the structures of the alpha helix and beta pleated sheet

118) Which of the choices is a major component of the secondary structure of keratin found in hair?

A) β-pleated sheets

B) α-pleated sheets

C) α-helix

D) β-helix

E) cylinder

Diff: 2

Learning Objective: 25.7 Describe the primary, secondary, tertiary, and quaternary structures of proteins, and the structures of the alpha helix and beta pleated sheet

119) Which of the given side chain interactions results in the tertiary structure of a protein?

A) hydrogen bonding

B) salt bridges

C) disulfide linkages

D) hydrophobic interactions

E) all of these

Diff: 1

Learning Objective: 25.7 Describe the primary, secondary, tertiary, and quaternary structures of proteins, and the structures of the alpha helix and beta pleated sheet

120) Heating of proteins results in loss of activity and the process is referred to as ________.

A) hydrolysis

B) denaturation

C) sequencing

D) hydrophobic interactions

E) covalent bonding

Diff: 1

Learning Objective: 25.7 Describe the primary, secondary, tertiary, and quaternary structures of proteins, and the structures of the alpha helix and beta pleated sheet

121) Denaturation of proteins results in loss of ________ structure.

A) primary

B) secondary

C) tertiary

D) B and C

E) A, B and C

Diff: 1

Learning Objective: 25.7 Describe the primary, secondary, tertiary, and quaternary structures of proteins, and the structures of the alpha helix and beta pleated sheet

122) Denaturation is ________.

A) irreversible

B) reversible with heat

C) reversible with a catalyst

D) reversible with UV

E) reversible under the same conditions

Diff: 1

Learning Objective: 25.7 Describe the primary, secondary, tertiary, and quaternary structures of proteins, and the structures of the alpha helix and beta pleated sheet

123) Cooking an egg is an example of ________, and is irreversible.

Diff: 1

Learning Objective: 25.7 Describe the primary, secondary, tertiary, and quaternary structures of proteins, and the structures of the alpha helix and beta pleated sheet

124) The quaternary structure of a protein is due to ________.

A) hydrogen bonding within the peptide

B) aggregation of two or more polypeptides

C) disulfide linkages within the peptide

D) covalent bonding between peptides

Diff: 1

Learning Objective: 25.7 Describe the primary, secondary, tertiary, and quaternary structures of proteins, and the structures of the alpha helix and beta pleated sheet

125) In a quaternary structure, the nonpolar groups are attracted to each other with ________.

A) hydrogen bonding

B) van der Waals interactions

C) ion-dipole interactions

D) dipole-dipole interactions

E) covalent bonding

Diff: 1

Learning Objective: 25.7 Describe the primary, secondary, tertiary, and quaternary structures of proteins, and the structures of the alpha helix and beta pleated sheet

126) Proteins that consist of linear polypeptide chains bundled together are classified as ________.

A) globular proteins

B) fibrous proteins

C) lipoproteins

D) tetrapeptides

E) pleated sheets

Diff: 1

Learning Objective: 25.8 Discuss the structures and functions of fibrous, globular, structural, and transport proteins and enzymes

127) Proteins that are chains that are coiled into compact shapes are classified as ________.

A) globular proteins

B) fibrous proteins

C) lipoproteins

D) tetrapeptides

E) pleated sheets

Diff: 1

Learning Objective: 25.8 Discuss the structures and functions of fibrous, globular, structural, and transport proteins and enzymes

128) α-Keratin found in hair, nails, and feathers is classified as ________.

A) globular protein

B) fibrous protein

C) structural protein

D) B and C

E) none of these

Diff: 1

Learning Objective: 25.8 Discuss the structures and functions of fibrous, globular, structural, and transport proteins and enzymes

129) α-Keratin found in nails has more strength than α-keratin found in hair due to the presence of more ________.

A) hydrophobic interactions

B) salt bridges

C) α-helix

D) disulfide bridges

E) pleated sheets

Diff: 2

Learning Objective: 25.8 Discuss the structures and functions of fibrous, globular, structural, and transport proteins and enzymes

130) Proteins that catalyze biochemical reactions are called ________.

A) apoproteins

B) peptides

C) enzymes

D) transport proteins

E) cellular proteins

Diff: 1

Learning Objective: 25.8 Discuss the structures and functions of fibrous, globular, structural, and transport proteins and enzymes

131) Hemoglobin, found in blood, is classified as a ________ protein.

A) structural

B) regulatory

C) transport

D) fibrous

E) globular

Diff: 1

Learning Objective: 25.8 Discuss the structures and functions of fibrous, globular, structural, and transport proteins and enzymes

132) The heme group present in hemoglobin is called a ________.

A) prosthetic group

B) substrate

C) cofactor

D) byfactor

E) enzyme

Diff: 1

Learning Objective: 25.8 Discuss the structures and functions of fibrous, globular, structural, and transport proteins and enzymes

133) ________ is a condition where the hemoglobin is distorted.

A) Malaria

B) Sickle cell anemia

C) Spina bifida

D) Thalassemia

E) Scabies

Diff: 1

Learning Objective: 25.8 Discuss the structures and functions of fibrous, globular, structural, and transport proteins and enzymes

134) How do enzymes speed up a reaction?

A) by changing the free energy of the reaction

B) by increasing the amount of energy released

C) by making reactions exergonic

D) by lowering the activation energy required

E) by adding heat to the reactants

Diff: 1

Learning Objective: 25.8 Discuss the structures and functions of fibrous, globular, structural, and transport proteins and enzymes

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