Question 1

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

Question 2

Which of the following compounds is not an amino acid?

Accepted Answer

A)   A
B)   B
C)   D
D)   CE) C) and D)
F) A) and D) A

Question 3

Hydrolase performs the following function:

Accepted Answer

A)   Catalyzes the hydrolysis of esters, amides, and other functional groups that are cleaved when they react with water
B)   Catalyzes the transfer of a group from one molecule to another
C)   Catalyzes the conversion of one isomer to another
D)   Catalyzes oxidation-reduction reactionsE) A) and B)
F) B) and C)

Question 4

Oxidoreductase performs the following function:

Accepted Answer

A)   Catalyzes the hydrolysis of esters, amides, and other functional groups that are cleaved when they react with water
B)   Catalyzes the transfer of a group from one molecule to another
C)   Catalyzes the conversion of one isomer to another
D)   Catalyzes oxidation-reduction reactionsE) B) and D)
F) All of the above

Question 5

What is the appropriate sequence of reaction conditions used to synthesize valine from acetamidomalonic ester? 2CH3; (2)  (CH3) 2CH2CHBr; (3)  HCl, H2O, heat B)  (1)  NaOCH2CH3; (2)  (CH3) 2CHBr; (3)  HCl, H2O, heat C)  (1)  NaOH; (2)  (CH3) 2CHBr; (3)  Cl2, H2O, heat D)  (1)  NaOH; (2)  CH3CH2CH2Br; (3)  HCl, H2O, heat" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   (1)  NaOCH2CH3; (2)  (CH3) 2CH2CHBr; (3)  HCl, H2O, heat
B)   (1)  NaOCH2CH3; (2)  (CH3) 2CHBr; (3)  HCl, H2O, heat
C)   (1)  NaOH; (2)  (CH3) 2CHBr; (3)  Cl2, H2O, heat
D)   (1)  NaOH; (2)  CH3CH2CH2Br; (3)  HCl, H2O, heatE) A) and B)
F) C) and D)

Question 6

Below is a proposed method for resolving a racemic mixture of (R) - and (S) -phenylalanine. Upon separation of the products, will this method produce (R) - or (S) -phenylalanine?

Accepted Answer

A)   (S) -Phenylalanine is produced since the acylase only hydrolyzes the amides of D-amino acids.
B)   (R) -Phenylalanine is produced since the acylase only hydrolyzes the amides of D-amino acids.
C)   (S) -Phenylalanine is produced since the acylase only hydrolyzes the amides of L-amino acids.
D)   (R) -Phenylalanine is produced since the acylase only hydrolyzes the amides of L-amino acids.E) A) and B)
F) A) and C)

Question 7

Reaction of a polypeptide, composed of 12 amino acids, with carboxypeptidase A releases Met (C-terminal amino acid) . The polypeptide undergoes partial hydrolysis to give 12 groups of peptides. Use the groups of overlapping amino acids to determine the proper sequence of this polypeptide.Note: Since these lists of peptides are separated by commas, they are not necessarily in the proper sequence.Ser, Lys, Trp-5. Met, Ala, Gly- 9. Lys, Ser
Gly, His, Ala-6. Ser, Lys, Val -10. Glu, His, Val
Glu, Val, Ser-7. Glu, His-11. Trp, Leu, Glu
Leu, Glu, Ser-8. Leu, Lys, Trp-12. Ala, Met

Accepted Answer

A)   Met-Ala-Gly-Glu-His-Ser-Val-Lys-Trp-Leu-Glu-Ser
B)   Met-Ala-Gly-His-Glu-Val-Ser-Lys-Trp-Leu-Glu-Ser
C)   Ser-Lys-Leu-Trp-Lys-Ser-Val-His-Glu-Gly-Ala-Met
D)   Ser-Glu-Leu-Trp-Lys-Ser-Val-Glu-His-Gly-Ala-MetE) B) and C)
F) A) and D) D

Question 8

Which of the following correctly describes the Merrifield synthesis?

Accepted Answer

A)   It uses BOC (tert-butoxycarbonyl)  as a protecting group for peptide synthesis.
B)   It uses a solid phase technique for the synthesis of peptides.
C)   It uses aqueous phase techniques for the synthesis of large polypeptides.
D)   It uses DCC (dicyclohexylcarbodiimide)  to form the amide bond in a peptide synthesis.E) B) and C)
F) A) and D)

Question 9

Transferase performs the following function:

Accepted Answer

A)   Catalyzes the transfer of a group from one molecule to another
B)   Catalyzes oxidation-reduction reactions
C)   Catalyzes the conversion of one isomer to another
D)   Catalyzes the hydrolysis of esters, amides, and other functional groups that are cleaved when they react with waterE) A) and B)
F) A) and C) A

Question 10

Amino acid synthesis is possible by allexcept one of the pathways listed. Which isnot a synthetic pathway for amino acids?

Accepted Answer

A)   SN2 reaction using an a-halo carboxylic acid with ammonia as the nucleophile
B)   Reaction of NH4Cl and NaCN with an aldehyde followed by an acidic work-up
C)   Nucleophilic addition of NH3 to an aldehyde followed by addition of cyanide to the imine, and, finally, hydrolysis
D)   Amination of malonic ester followed by hydrolysis and decarboxylationE) B) and C)
F) None of the above

Question 11

Iosmerase performs the following function:

Accepted Answer

A)   Catalyzes the hydrolysis of esters, amides, and other functional groups that are cleaved when they react with water
B)   Catalyzes the conversion of one isomer to another
C)   Catalyzes oxidation-reduction reactions
D)   Catalyzes the transfer of a group from one molecule to anotherE) A) and B)
F) All of the above

Exam 22: Amino Acids and Proteins

Correct Answer
verified

Which of the following compounds is not an amino acid?

Correct Answer
verified
A

Hydrolase performs the following function:

Correct Answer
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Oxidoreductase performs the following function:

Correct Answer
verified

What is the appropriate sequence of reaction conditions used to synthesize valine from acetamidomalonic ester?

Correct Answer
verified

Below is a proposed method for resolving a racemic mixture of (R) - and (S) -phenylalanine. Upon separation of the products, will this method produce (R) - or (S) -phenylalanine?

Correct Answer
verified

Correct Answer
verified
D

Which of the following correctly describes the Merrifield synthesis?

Correct Answer
verified

Transferase performs the following function:

Correct Answer
verified
A

Amino acid synthesis is possible by allexcept one of the pathways listed. Which isnot a synthetic pathway for amino acids?

Correct Answer
verified

Iosmerase performs the following function:

Correct Answer
verified

Exam 22: Amino Acids and Proteins

Correct AnswerverifiedShow Answer

Which of the following compounds is not an amino acid?

Correct AnswerverifiedA

Hydrolase performs the following function:

Correct AnswerverifiedShow Answer

Oxidoreductase performs the following function:

Correct AnswerverifiedShow Answer

What is the appropriate sequence of reaction conditions used to synthesize valine from acetamidomalonic ester?

Correct AnswerverifiedShow Answer

Below is a proposed method for resolving a racemic mixture of (R) - and (S) -phenylalanine. Upon separation of the products, will this method produce (R) - or (S) -phenylalanine?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedD

Which of the following correctly describes the Merrifield synthesis?

Correct AnswerverifiedShow Answer

Transferase performs the following function:

Correct AnswerverifiedA

Amino acid synthesis is possible by allexcept one of the pathways listed. Which isnot a synthetic pathway for amino acids?

Correct AnswerverifiedShow Answer

Iosmerase performs the following function:

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
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A

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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D

Correct Answer
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Correct Answer
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A

Correct Answer
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Correct Answer
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