Question 1

What is the net charge on the dipeptide lys-asp at a  pH\mathrm{pH}pH  of 1.0 ?
Aspartic acid  (R=−CH2CO2H) \left(\mathrm{R}=-\mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}\right) (R=−CH2​CO2​H)  
Lysine (  R=CH2CH2CH2CH2NH2) \left.\mathrm{R}=\mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}\right) R=CH2​CH2​CH2​CH2​NH2​)

Accepted Answer

A)   +1
B)   +2
C)   +3
D)   +4 E) B) and C)
F) A) and D)

Question 2

Which of the following is the zwitterion form of L-alanine?

Accepted Answer

A)   
B)  
C)   
D)   E) A) and D)
F) C) and D)

Question 3

Which one of the following is the final product of the reaction sequence shown below?

Accepted Answer

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

Question 4

A pentapeptide was found to contain the amino acids ala, gly, met, phe, and ser. Partial hydrolysis of the pentapeptide gave the dipeptides gly-ser, met-phe, ala-gly, and ser-met. What is the sequence of the pentapeptide?

Accepted Answer

A)   gly-ser-met-phe-ala
B)   gly-ser-met-ala-phe
C)   ala-gly-ser-phe-met
D)   ala-gly-ser-met-pheE) C) and D)
F) A) and B)

Question 5

Which one of the following reagents is used for the visual detection of amino acids?

Accepted Answer

A)   Sanger's reagent
B)   dicyclohexylcarbodiimide (DCCI) 
C)   ninhydrin
D)   phenyl isothiocyanateE) A) and D)
F) A) and B)

Question 6

Which of the following is the major product of the reaction shown below? (the  pKa’s \mathrm{p} K_{\mathrm{a}}{ }^{	ext {&#x27;s }}pKa​’s   are shown)

Accepted Answer

A)   
B)  
C)   
D)   E) None of the above
F) All of the above

Question 7

What is the net charge on L-aspartic acid  (R=−CH2CO2H) \left(\mathrm{R}=-\mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}\right) (R=−CH2​CO2​H)   at a pH of 11.0 ?

Accepted Answer

A)   +1
B)   +2
C)   -1
D)   -2 E) A) and B)
F) C) and D)

Question 8

In strongly acidic solution L-lysine is primarily a dication as shown below. As the  pH\mathrm{pH}pH  is raised, which proton is lost to form the monocation?

Accepted Answer

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

Question 9

Which of the following is the DNP derivative obtained from the reaction sequence shown below?

Accepted Answer

A)  
B)  
C)   
D)   E) A) and C)
F) C) and D) A

Question 10

Linus Pauling is credited with describing the  α\alphaα -helix structure of a polypeptide. The  α\alphaα -helix is an example of a polypeptide's

Accepted Answer

A)   primary structure.
B)   secondary structure.
C)   tertiary structure.
D)   quaternary structure. E) None of the above
F) A) and B)

Question 11

Identify the missing starting reagent needed in the Strecker synthesis of isoleucine. (Assume you will get all the stereoisomers of isoleucine.)

Accepted Answer

A)    
B)   
C)   
D)   E) A) and B)
F) A) and C)

Question 12

What is the total number of different tripeptides which can result from three different L-amino acids?

Accepted Answer

A)   three
B)   four
C)   six
D)   nineE) B) and C)
F) A) and B)

Question 13

Which of the following is the abbreviated formula of the tetrapeptide shown below? (Hint: Remember to start at the  N\mathrm{N}N -terminal end.)

Accepted Answer

A)   lys-ser-asp-ala
B)   ser-lys-ala-asp
C)   asp-ala-ser-lys
D)   asp-ser-ala-lys E) B) and C)
F) C) and D)

Question 14

In aqueous solution, the artificial sweetener aspartame slowly converts to the cyclic compound shown below. Which of the following best describes this reaction?

Accepted Answer

A)   nucleophilic acyl substitution
B)   Dieckmann condensation
C)   ester hydrolysis
D)    SN2\mathrm{S}_{\mathrm{N}} 2SN​2  reaction E) A) and B)
F) A) and C)

Question 15

The Fischer projection shown below denotes a amino acid which has the configuration.

Accepted Answer

A)   D, S
B)   D, R
C)   L, S
D)   L, RE) A) and D)
F) B) and C)

Question 16

What is the pI of valine, shown below? (the  pKa\mathrm{p} K_{\mathrm{a}}pKa​  's are shown)

Accepted Answer

A)   2.32
B)   4.81
C)   5.97
D)   9.62 E) A) and C)
F) None of the above

Exam 25: Amino Acids, Peptides, and Proteins

What is the net charge on the dipeptide lys-asp at a $\mathrm{pH}$ of 1.0 ? Aspartic acid $\left(\mathrm{R}=-\mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}\right)$ Lysine ( $\left.\mathrm{R}=\mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}\right)$

Correct Answer
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Which of the following is the zwitterion form of L-alanine?

Correct Answer
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Which one of the following is the final product of the reaction sequence shown below?

Correct Answer
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B

A pentapeptide was found to contain the amino acids ala, gly, met, phe, and ser. Partial hydrolysis of the pentapeptide gave the dipeptides gly-ser, met-phe, ala-gly, and ser-met. What is the sequence of the pentapeptide?

Correct Answer
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Which one of the following reagents is used for the visual detection of amino acids?

Correct Answer
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Which of the following is the major product of the reaction shown below? (the $\mathrm{p} K_{\mathrm{a}}{ }^{\text {'s }}$ are shown) $Which of the following is the major product of the reaction shown below? (the \mathrm{p} K_{\mathrm{a}}{ }^{\text {'s }} are shown) A) B) C) D)$

Correct Answer
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What is the net charge on L-aspartic acid $\left(\mathrm{R}=-\mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}\right)$ at a pH of 11.0 ?

Correct Answer
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B

Which of the following is the DNP derivative obtained from the reaction sequence shown below?

Correct Answer
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A

Linus Pauling is credited with describing the $\alpha$ -helix structure of a polypeptide. The $\alpha$ -helix is an example of a polypeptide's

Correct Answer
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Identify the missing starting reagent needed in the Strecker synthesis of isoleucine. (Assume you will get all the stereoisomers of isoleucine.)

Correct Answer
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What is the total number of different tripeptides which can result from three different L-amino acids?

Correct Answer
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Correct Answer
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The Fischer projection shown below denotes a amino acid which has the configuration.

Correct Answer
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What is the pI of valine, shown below? (the $\mathrm{p} K_{\mathrm{a}}$ 's are shown) $What is the pI of valine, shown below? (the \mathrm{p} K_{\mathrm{a}} 's are shown) A) 2.32 B) 4.81 C) 5.97 D) 9.62$

Correct Answer
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Exam 25: Amino Acids, Peptides, and Proteins

Correct AnswerverifiedShow Answer

Which of the following is the zwitterion form of L-alanine?

Correct AnswerverifiedShow Answer

Which one of the following is the final product of the reaction sequence shown below?

Correct AnswerverifiedB

A pentapeptide was found to contain the amino acids ala, gly, met, phe, and ser. Partial hydrolysis of the pentapeptide gave the dipeptides gly-ser, met-phe, ala-gly, and ser-met. What is the sequence of the pentapeptide?

Correct AnswerverifiedShow Answer

Which one of the following reagents is used for the visual detection of amino acids?

Correct AnswerverifiedShow Answer

Which of the following is the major product of the reaction shown below? (the pKa’s \mathrm{p} K_{\mathrm{a}}{ }^{\text {'s }}pKa​’s are shown)

Correct AnswerverifiedShow Answer

What is the net charge on L-aspartic acid (R=−CH2CO2H) \left(\mathrm{R}=-\mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}\right) (R=−CH2​CO2​H) at a pH of 11.0 ?

Correct AnswerverifiedShow Answer

In strongly acidic solution L-lysine is primarily a dication as shown below. As the pH\mathrm{pH}pH is raised, which proton is lost to form the monocation?

Correct AnswerverifiedB

Which of the following is the DNP derivative obtained from the reaction sequence shown below?

Correct AnswerverifiedA

Linus Pauling is credited with describing the α\alphaα -helix structure of a polypeptide. The α\alphaα -helix is an example of a polypeptide's

Correct AnswerverifiedShow Answer

Identify the missing starting reagent needed in the Strecker synthesis of isoleucine. (Assume you will get all the stereoisomers of isoleucine.)

Correct AnswerverifiedShow Answer

What is the total number of different tripeptides which can result from three different L-amino acids?

Correct AnswerverifiedShow Answer

Which of the following is the abbreviated formula of the tetrapeptide shown below? (Hint: Remember to start at the N\mathrm{N}N -terminal end.)

Correct AnswerverifiedShow Answer

In aqueous solution, the artificial sweetener aspartame slowly converts to the cyclic compound shown below. Which of the following best describes this reaction?

Correct AnswerverifiedShow Answer

The Fischer projection shown below denotes a amino acid which has the configuration.

Correct AnswerverifiedShow Answer

What is the pI of valine, shown below? (the pKa\mathrm{p} K_{\mathrm{a}}pKa​ 's are shown)

Correct AnswerverifiedShow Answer

Correct Answer
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Correct Answer
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Correct Answer
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B

Correct Answer
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Correct Answer
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Which of the following is the major product of the reaction shown below? (the $\mathrm{p} K_{\mathrm{a}}{ }^{\text {'s }}$ are shown) $Which of the following is the major product of the reaction shown below? (the \mathrm{p} K_{\mathrm{a}}{ }^{\text {'s }} are shown) A) B) C) D)$

Correct Answer
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What is the net charge on L-aspartic acid $\left(\mathrm{R}=-\mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}\right)$ at a pH of 11.0 ?

Correct Answer
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Correct Answer
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B

Correct Answer
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A

Linus Pauling is credited with describing the $\alpha$ -helix structure of a polypeptide. The $\alpha$ -helix is an example of a polypeptide's

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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Correct Answer
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What is the pI of valine, shown below? (the $\mathrm{p} K_{\mathrm{a}}$ 's are shown) $What is the pI of valine, shown below? (the \mathrm{p} K_{\mathrm{a}} 's are shown) A) 2.32 B) 4.81 C) 5.97 D) 9.62$

Correct Answer
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