Question 1

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) A) and B)
F) B) and C)

Question 2

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) B) and C)
F) A) and C)

Question 3

Why do amide bonds exist as reasonably stable s-cis or s-trans isomers at room temperature?

Accepted Answer

A)  These amide bonds are not stable.
B)  There is partial double bond character between the carbonyl carbon and the nitrogen atom.
C)  The oxygen atom is hydrogen-bonded with the nitrogen atom.
D)  The side-chains can form hydrogen bonds.E) A) and B)
F) A) and C)

Question 4

Which of the following amino acids does not have an L-isomer?

Accepted Answer

A)  Alanine
B)  Valine
C)  Glycine
D)  LeucineE) A) and D)
F) A) and C)

Question 5

What is the major organic product for the following reaction?

Accepted Answer

A)  I
B)  II
C)  III
D)  IVE) All of the above
F) B) and C)

Question 6

Below is a 2D chromatogram that shows the separation of five amino acids.In this technique,the amino acid mixture is first separated by chromatography using a polar solvent system.Then the plate is rotated 90°,and the amino acids are further separated by electrophoresis.Identify the spots obtained from a mixture of Trp,Glu,Lys,Ile and Thr.A table with isoelectric points is included to aid in solving this problem.  amino acid-pI value Trp-5.9
Glu-3.2
Lys-9.7
Ile-6.0
Thr-5.6

Accepted Answer

A)  1=Lys,2=Thr,3=Glu,4=Trp,5=Ile
B)  1=Glu,2=Thr,3=Lys,4=Trp,5=Ile
C)  1=Lys,2=Ile,3=Glu,4=Trp,5=Thr
D)  1=Glu,2=Ile,3=Lys,4=Trp,5=ThrE) None of the above
F) B) and D)

Question 7

Which of the following compounds is not an amino acid?

Accepted Answer

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

Question 8

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

Accepted Answer

A)  Keratins
B)  Hormones
C)  Enzymes
D)  AntibodiesE) A) and B)
F) A) and C)

Question 9

Why is the s-trans form of an amide bond more stable?

Accepted Answer

A)  There is no s-cis form in an amide bond.
B)  The oxygen is hydrogen-bonded with the nitrogen atom.
C)  The nitrogen is able to be sp2-hybridized.
D)  The more sterically bulky groups are farther apart.E) A) and B)
F) B) and C) D

Question 10

What reagents would you use to convert acetaldehyde into alanine?

Accepted Answer

A)  NH3
B)  HCN
C)  NaCN,NH4Cl
D)  NaNH2E) All of the above
F) A) and B)

Question 11

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) All of the above

Question 12

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) A) and C)
F) A) and D)

Question 13

Which of the following amino acids is achiral?

Accepted Answer

A)  Phenylalanine
B)  Glycine
C)  Valine
D)  AlanineE) All of the above
F) A) and B)

Question 14

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

Accepted Answer

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

Question 15

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

Accepted Answer

A)  Hemoglobin
B)  Keratins
C)  Collagens
D)  ElastinsE) A) and B)
F) A) and D) A

Question 16

Which of the following aldehydes would be a good starting material in the Strecker synthesis of phenylalanine?

Accepted Answer

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

Question 17

Which is the correct structure for the amino acid valine?

Accepted Answer

A)  A
B)  B
C)  C
D)  DE) B) and C)
F) All of the above

Question 18

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 19

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

Accepted Answer

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

Question 20

What is the major organic product for the following reaction?

Accepted Answer

A)  A
B)  B
C)  C
D)  DE) A) and B)
F) B) and C) A

Exam 27: Amino Acids and Proteins

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

Correct Answer
verified

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

Correct Answer
verified

Why do amide bonds exist as reasonably stable s-cis or s-trans isomers at room temperature?

Correct Answer
verified

Which of the following amino acids does not have an L-isomer?

Correct Answer
verified

What is the major organic product for the following reaction?

Correct Answer
verified

Correct Answer
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Which of the following compounds is not an amino acid?

Correct Answer
verified

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

Correct Answer
verified

Why is the s-trans form of an amide bond more stable?

Correct Answer
verified
D

What reagents would you use to convert acetaldehyde into alanine?

Correct Answer
verified

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
verified

Which of the following correctly describes the Merrifield synthesis?

Correct Answer
verified

Which of the following amino acids is achiral?

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified
A

Which of the following aldehydes would be a good starting material in the Strecker synthesis of phenylalanine?

Correct Answer
verified

Which is the correct structure for the amino acid valine?

Correct Answer
verified

What is the configuration of naturally occurring amino acids?

Correct Answer
verified

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

Correct Answer
verified

What is the major organic product for the following reaction?

Correct Answer
verified
A

Exam 27: Amino Acids and Proteins

Which of the following correctly describes 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

Why do amide bonds exist as reasonably stable s-cis or s-trans isomers at room temperature?

Correct AnswerverifiedShow Answer

Which of the following amino acids does not have an L-isomer?

Correct AnswerverifiedShow Answer

What is the major organic product for the following reaction?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which of the following compounds is not an amino acid?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Why is the s-trans form of an amide bond more stable?

Correct AnswerverifiedD

What reagents would you use to convert acetaldehyde into alanine?

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

Which of the following correctly describes the Merrifield synthesis?

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

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

Correct AnswerverifiedA

Which of the following aldehydes would be a good starting material in the Strecker synthesis of phenylalanine?

Correct AnswerverifiedShow Answer

Which is the correct structure for the amino acid valine?

Correct AnswerverifiedShow Answer

What is the configuration of naturally occurring amino acids?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

What is the major organic product for the following reaction?

Correct AnswerverifiedA

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D

Correct 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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A

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A