Question 1

Which of the following is the major advantage of the Merrifield synthesis of peptides?

Accepted Answer

A)  It allows for the formation of absolutely no by-products.
B)  Impurities can be easily washed away.
C)  Excess reagent can be used.
D)  It prevents hydrogenation.E) C) and D)
F) All of the above

Question 2

What are the only covalent bonds that stabilize the tertiary structure of a peptide?

Accepted Answer

A)  Hydrogen bonds
B)  Disulfide bonds
C)  Van der Waal bonds
D)  Ionic bondsE) A) and B)
F) A) and C)

Question 3

What is the configuration of naturally occurring amino acids?

Accepted Answer

A)  D
B)  S
C)  L
D)  RE) B) and C)
F) All of the above

Question 4

Which of the following compounds is not an amino acid?

Accepted Answer

A)  A
B)  B
C)  C
D)  DE) A) and B)
F) None of the above

Question 5

What is the IUPAC or common name for the following compound?

Accepted Answer

A)  Cysteinylalanine
B)  Alanylcysteine
C)  Serinylalanine
D)  AlanylserineE) B) and C)
F) All of the above

Question 6

What is the product of the following reaction? (Assume workup to neutralize.)

Accepted Answer

A)  I
B)  II
C)  III
D)  IVE) A) and D)
F) A) and C)

Question 7

What amino acid is at the C-terminus of the following peptide?

Accepted Answer

A)  Valine
B)  Serine
C)  Alanine
D)  ProlineE) B) and C)
F) A) and C)

Question 8

Which of the following correctly describes the Merrifield synthesis?

Accepted Answer

A)  It uses a solid phase technique for the synthesis of peptides.
B)  It uses DCC (dicyclohexylcarbodiimide) to form the amide bond in a peptide synthesis.
C)  It uses BOC (tert-butoxycarbonyl) as a protecting group for peptide synthesis.
D)  It uses aqueous phase techniques for the synthesis of large polypeptides.E) None of the above
F) B) and D)

Question 9

Give the order (1st to last) in which the following amino acids would be eluted with a buffer of pH = 4 from a column containing a cationic-exchange resin (Dowex 50) : Arg (pI = 10.8) ,Ser (pI = 5.7) ,Asp (pI = 2.8) and His (pI = 7.6) .

Accepted Answer

A)  His,Ser,Asp,Arg
B)  Arg,His,Ser,Asp
C)  His,Ser,Arg,Asp
D)  Asp,Ser,His,ArgE) A) and B)
F) A) and C)

Question 10

Why can glycine not be resolved into two enantiomers?

Accepted Answer

A)  It has no stereogenic centers.
B)  It has no nitrogen atoms.
C)  It has no aromatic rings.
D)  It cannot be converted into a salt.E) C) and D)
F) All of the above

Question 11

Which of the following is (are) fibrous protein(s) ?

Accepted Answer

A)  Keratins
B)  Hormones
C)  Enzymes
D)  AntibodiesE) None of the above
F) All of the above

Question 12

Which of the following correctly describes the tertiary structure of a peptide?

Accepted Answer

A)  the three-dimensional conformations of localized regions of a protein
B)  the particular sequence of amino acids that are joined together by peptide bonds
C)  the structure is defined by the b-pleated sheet form
D)  the three-dimensional shape adopted by the entire peptideE) None of the above
F) B) and C)

Question 13

Which is the correct structure for the amino acid cysteine?

Accepted Answer

A)  A
B)  B
C)  C
D)  DE) A) and D)
F) None of the above

Question 14

What is formed by the combination of four amino acids?

Accepted Answer

A)  A protein
B)  A polypeptide
C)  A tripeptide
D)  A tetrapeptideE) B) and D)
F) B) and C)

Question 15

What is the product of the following reaction? (Assume workup to neutralize.)

Accepted Answer

A)  I
B)  II
C)  III
D)  IVE) B) and C)
F) A) and B)

Question 16

Which of the following correctly describes a peptide bond?

Accepted Answer

A)  a bond between sp3-hybridized atoms only
B)  a bond usually found in the s-cis conformation
C)  an amide bond
D)  the result of the formation of the carbonyl group of one amino acid with a R-group from the other amino acidE) A) and B)
F) A) and D)

Question 17

What is the product of the following reaction? (Assume workup to neutralize.)

Accepted Answer

A)  I
B)  II
C)  III
D)  IVE) A) and B)
F) None of the above

Question 18

Which of the following is the correct structure for aspartic acid at pH = 1?

Accepted Answer

A)  A
B)  B
C)  C
D)  DE) None of the above
F) B) and D)

Question 19

What is (are) the missing reagent(s) in the reaction below? 3 B) HCN C) NaCN,NH4Cl D) NaNH2" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  NH3
B)  HCN
C)  NaCN,NH4Cl
D)  NaNH2E) B) and D)
F) A) and D)

Question 20

Which of the following amino acids is achiral?

Accepted Answer

A)  Phenylalanine
B)  Glycine
C)  Valine
D)  AlanineE) C) and D)
F) A) and B)

Exam 27: Amino Acids and Proteins

Which of the following correctly describes a peptide bond?

Correct AnswerverifiedShow Answer

Which of the following compounds is not an amino acid?

Correct AnswerverifiedShow Answer

What is the configuration of naturally occurring amino acids?

Correct AnswerverifiedShow Answer

Which of the following correctly describes the Merrifield synthesis?

Correct AnswerverifiedShow Answer

What is the product of the following reaction? (Assume workup to neutralize.)

Correct AnswerverifiedShow Answer

Which of the following correctly describes the tertiary structure of a peptide?

Correct AnswerverifiedShow Answer

What is the product of the following reaction? (Assume workup to neutralize.)

Correct AnswerverifiedShow Answer

What is formed by the combination of four amino acids?

Correct AnswerverifiedShow Answer

Which of the following is the correct structure for aspartic acid at pH = 1?

Correct AnswerverifiedShow Answer

Which of the following is (are) fibrous protein(s) ?

Correct AnswerverifiedShow Answer

Which of the following amino acids is achiral?

Correct AnswerverifiedShow Answer

What is the product of the following reaction? (Assume workup to neutralize.)

Correct AnswerverifiedShow Answer

Why can glycine not be resolved into two enantiomers?

Correct AnswerverifiedShow Answer

Which is the correct structure for the amino acid cysteine?

Correct AnswerverifiedShow Answer

What is the IUPAC or common name for the following compound?

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What is (are) the missing reagent(s) in the reaction below?

Correct AnswerverifiedShow Answer

What are the only covalent bonds that stabilize the tertiary structure of a peptide?

Correct AnswerverifiedShow Answer

Which of the following is the major advantage of the Merrifield synthesis of peptides?

Correct AnswerverifiedShow Answer

What amino acid is at the C-terminus of the following peptide?

Correct AnswerverifiedShow Answer

Give the order (1st to last) in which the following amino acids would be eluted with a buffer of pH = 4 from a column containing a cationic-exchange resin (Dowex 50) : Arg (pI = 10.8) ,Ser (pI = 5.7) ,Asp (pI = 2.8) and His (pI = 7.6) .

Correct AnswerverifiedShow Answer

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Give the order (1^st to last) in which the following amino acids would be eluted with a buffer of pH = 4 from a column containing a cationic-exchange resin (Dowex 50) : Arg (pI = 10.8) ,Ser (pI = 5.7) ,Asp (pI = 2.8) and His (pI = 7.6) .

Correct Answer
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