Question 1

Which of the following amino acids migrates to the positive electrode on paper electrophoresis at a pH of 7.0?

Accepted Answer

A)  glutamic acid 
B)  arginine 
C)  lysine 
D)  histadine 
A)  glutamic acid 
B)  arginine 
C)  lysine 
D)  histadine

Question 2

Identify the function of the following group in protein synthesis. ​

Accepted Answer

A)  Protection 
B)  Hydrolysis 
C)  Hydrogenation 
D)  Alkylation 
A)  Protection 
B)  Hydrolysis 
C)  Hydrogenation 
D)  Alkylation

Question 3

The following structure is that of Sanger's reagent.

Accepted Answer

A) True 
 B)False

Question 4

What are the R/S designations of the two stereocenters of L-threonine?

Accepted Answer

A)  2R,3R 
B)  2R,3S 
C)  2S,3R 
D)  2S,3S 
A)  2R,3R 
B)  2R,3S 
C)  2S,3R 
D)  2S,3S

Question 5

Consider the following image.   This represents the tertiary structure of a protein.

Accepted Answer

A) True 
 B)False

Question 6

MATCH a structure from the list below to each of the following terms. Place the letter of the structure in the blank to the left of the term which it describes.
-_____ is a peptide coupling reagent.

Accepted Answer

A)   
B)   
C) Val−Phe−Leu−Met−Tyr−Pro−Gly−Trp−Cys−Glu 
D)   
E)  
F)Asp−Tyr−Ile−His−Pro−Phe−Arg−Val
G)BOC group
H) 
I) 
J) 
K) 
L)Val−Lys−Phe−Gly−Arg−Met−Arg−Phe
M)Z group 
A)   
B)   
C) Val−Phe−Leu−Met−Tyr−Pro−Gly−Trp−Cys−Glu 
D)   
E)  
F)Asp−Tyr−Ile−His−Pro−Phe−Arg−Val
G)BOC group
H) 
I) 
J) 
K) 
L)Val−Lys−Phe−Gly−Arg−Met−Arg−Phe
M)Z group

Question 7

Which of the following amino acids has a sulfhydryl group?

Accepted Answer

A)  serine 
B)  cysteine 
C)  lysine 
D)  tyrosine 
A)  serine 
B)  cysteine 
C)  lysine 
D)  tyrosine

Question 8

Which of the following dipeptides is L-Cys-L-Ala?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
A)  1 
B)  2 
C)  3 
D)  4

Question 9

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

Accepted Answer

A)  serine 
B)  valine 
C)  glycine 
D)  proline 
A)  serine 
B)  valine 
C)  glycine 
D)  proline

Question 10

In terms of the number of amino acid residues Cys-Ile-Ser-Asp-Gly-His-Gly-Gly would be classified as a(n) ________________.

Accepted Answer

The answer of In terms of the number of amino...

Question 11

To what structural feature does the term "tertiary structure" refer?

Accepted Answer

A)  the sequence of amino acids in proteins 
B)  the overall folding pattern of proteins 
C)  the aggregation of polypeptides 
D)  the conformation of local regions of polypeptides 
A)  the sequence of amino acids in proteins 
B)  the overall folding pattern of proteins 
C)  the aggregation of polypeptides 
D)  the conformation of local regions of polypeptides

Question 12

Which of the following is a definition of the isoelectric point of an amino acid?

Accepted Answer

A)  The pH at which an amino acid has no net charge 
B)  The pH at which the α-NH2 group is completely protonated 
C)  The melting point of an amino acid 
D)  The conductivity of a 1 M solution of an amino acid in water 
A)  The pH at which an amino acid has no net charge 
B)  The pH at which the α-NH2 group is completely protonated 
C)  The melting point of an amino acid 
D)  The conductivity of a 1 M solution of an amino acid in water

Question 13

Which of the following is not a strategy for the synthesis of polypeptides?

Accepted Answer

A)  Protect the a-amino group of the amino acid aa1 to reduce its nucleophilicity so that the group does not participate in nucleophilic addition to the carboxyl group of either aa1 or aa2. 
B)  Cleave the polypeptide at specific peptide bonds, determine the sequence of each fragment, and then match overlapping fragments to arrive at the sequence of the polypeptide. 
C)  Activate the a-carboxyl group of the amino acid aa1 so that the group is susceptible to nucleophilic attack by the a-amino group of aa2. 
D)  Protect the a-carboxyl group of the amino acid aa2 so that the amino acid is not susceptible to nucleophilic attack by the a-amino group of another molecule of aa2. 
A)  Protect the a-amino group of the amino acid aa1 to reduce its nucleophilicity so that the group does not participate in nucleophilic addition to the carboxyl group of either aa1 or aa2. 
B)  Cleave the polypeptide at specific peptide bonds, determine the sequence of each fragment, and then match overlapping fragments to arrive at the sequence of the polypeptide. 
C)  Activate the a-carboxyl group of the amino acid aa1 so that the group is susceptible to nucleophilic attack by the a-amino group of aa2. 
D)  Protect the a-carboxyl group of the amino acid aa2 so that the amino acid is not susceptible to nucleophilic attack by the a-amino group of another molecule of aa2.

Question 14

What is the approximate value of the pKa of the α-NH3+ of amino acids?

Accepted Answer

A)  2 
B)  5 
C)  9 
D)  12 
A)  2 
B)  5 
C)  9 
D)  12

Question 15

In the Edman degradation analysis of the N-terminus of a peptide the terminal residue reacts with phenyl isocyanate, an example is shown below. Provide the structure of both of the products of this reaction.

Accepted Answer

The answer of In the Edman degradation analysis of the...

Question 16

The Edman degradation is used to identify the ___-terminal amino acid of a peptide.

Accepted Answer

The answer of The Edman degradation is used to identify...

Question 17

The structure of the phenylhydantoin derived from the _____ cycle of the Edman degradation of Phe-Ala-Ser is

Accepted Answer

The answer of The structure of the phenylhydantoin derived from...

Exam 27: Amino Acids and Proteins

Which of the following amino acids migrates to the positive electrode on paper electrophoresis at a pH of 7.0?

Identify the function of the following group in protein synthesis. ​

The following structure is that of Sanger's reagent.

What are the R/S designations of the two stereocenters of L-threonine?

Consider the following image. This represents the tertiary structure of a protein.

MATCH a structure from the list below to each of the following terms. Place the letter of the structure in the blank to the left of the term which it describes. -_____ is a peptide coupling reagent.

Which of the following amino acids has a sulfhydryl group?

Which of the following dipeptides is L-Cys-L-Ala?

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

In terms of the number of amino acid residues Cys-Ile-Ser-Asp-Gly-His-Gly-Gly would be classified as a(n) ________________.

To what structural feature does the term "tertiary structure" refer?

Which of the following is a definition of the isoelectric point of an amino acid?

Which of the following is not a strategy for the synthesis of polypeptides?

What is the approximate value of the pKa of the α-NH3+ of amino acids?

In the Edman degradation analysis of the N-terminus of a peptide the terminal residue reacts with phenyl isocyanate, an example is shown below. Provide the structure of both of the products of this reaction.

The Edman degradation is used to identify the ___-terminal amino acid of a peptide.

The structure of the phenylhydantoin derived from the _____ cycle of the Edman degradation of Phe-Ala-Ser is

Covalent Bonding and Shapes of Molecules

Alkanes and Cycloalkanes

Stereoisomerism and Chirality

Acids and Bases

Alkenes: Bonding, Nomenclature, and Properties

Reactions of Alkenes

Alkynes

Haloalkanes, Halogenation, and Radical Reactions

Nucleophilic Substitution and Beta-Elimination

Alcohols

Ethers, Epoxides, and Sulfides

Infrared Spectroscopy

Nuclear Magnetic Resonance Spectroscopy

Mass Spectrometry

An Introduction to Organometallic Compounds

Aldehydes and Ketones

Carboxylic Acids

Functional Derivatives of Carboxylic Acids

Enolate Anions and Enamines

Dienes, Conjugated Systems, and Pericyclic Reactions

Benzene and the Concept of Aromaticity

Reactions of Benzene and Its Derivatives

Amines

Catalytic Carbon-Carbon Bond Formation

Carbohydrates

Lipids

Nucleic Acids

Organic Polymer Chemistry

Filters

Identify the function of the following group in protein synthesis.

What is the approximate value of the pK_a of the α-NH₃⁺ of amino acids?