Question 1

Provide a structure of the dipeptide Ser-Gly-Asp at biological pH.

Accepted Answer

The answer of Provide a structure of the dipeptide Ser-Gly-Asp...

Question 2

Which amino acid's side chain is negatively charged at biological pH?

Accepted Answer

A)  arginine 
B)  tyrosine 
C)  aspartic acid 
D)  serine 
E)  glutamine 
A)  arginine 
B)  tyrosine 
C)  aspartic acid 
D)  serine 
E)  glutamine

Question 3

Provide the structure of the predominant form of L-methionine present in an aqueous solution at biological pH.

Accepted Answer

The answer of Provide the structure of the predominant form...

Question 4

What is the one letter symbol of the amino acid below?

Accepted Answer

A)  G 
B)  Q 
C)  W 
D)  T 
E)  F 
A)  G 
B)  Q 
C)  W 
D)  T 
E)  F

Question 5

What is the name of the amino acid produced when propanoic acid is subjected to the following sequence of reagents: 1. PBr3, Br2; 2. H2O; 3. NH3, Δ?

Accepted Answer

A)  alanine 
B)  aspartic acid 
C)  glutamic acid 
D)  valine 
E)  asparagine 
A)  alanine 
B)  aspartic acid 
C)  glutamic acid 
D)  valine 
E)  asparagine

Question 6

Draw the Fischer projection of L-glutamic acid at a pH of 2.

Accepted Answer

The answer of Draw the Fischer projection of L-glutamic acid...

Question 7

Provide the major organic product in the reaction of L-methionine with benzyl chloroformate.

Accepted Answer

The answer of Provide the major organic product in the...

Question 8

Provide the structure of the predominant form of L-valine present in an aqueous solution at biological pH.

Accepted Answer

The answer of Provide the structure of the predominant form...

Question 9

Which of the following amino acids has a nonpolar side chain?

Accepted Answer

A)  serine 
B)  aspartic acid 
C)  asparagine 
D)  threonine 
E)  leucine 
A)  serine 
B)  aspartic acid 
C)  asparagine 
D)  threonine 
E)  leucine

Question 10

Amides are:

Accepted Answer

A)  the most reactive acid derivative. 
B)  the most acidic acid derivative. 
C)  the most stable acid derivative. 
D)  the least stable acid derivative. 
E)  both A and D 
A)  the most reactive acid derivative. 
B)  the most acidic acid derivative. 
C)  the most stable acid derivative. 
D)  the least stable acid derivative. 
E)  both A and D

Question 11

If the side chain of asparagine is hydrolyzed, what amino acid is formed?

Accepted Answer

The answer of If the side chain of asparagine is...

Question 12

Which of the following arrangements is usually not found in the secondary structure of proteins?

Accepted Answer

A)  α-helix 
B)  double helix 
C)  random coil 
D)  pleated sheet 
A)  α-helix 
B)  double helix 
C)  random coil 
D)  pleated sheet

Question 13

Which of the following amino acids has a side chain which contains a nonbasic nitrogen?

Accepted Answer

A)  proline 
B)  glutamine 
C)  histidine 
D)  tyrosine 
E)  lysine 
A)  proline 
B)  glutamine 
C)  histidine 
D)  tyrosine 
E)  lysine

Question 14

When a disulfide linkage is formed, the compound containing this new linkage has been ________.

Accepted Answer

A)  oxidized 
B)  reduced 
C)  electrolyzed 
D)  hydrolyzed 
E)  dehydrated 
A)  oxidized 
B)  reduced 
C)  electrolyzed 
D)  hydrolyzed 
E)  dehydrated

Question 15

Provide a structure of the dipeptide Gly-Asp-Leu at biological pH.

Accepted Answer

The answer of Provide a structure of the dipeptide Gly-Asp-Leu...

Question 16

Provide a synthesis of racemic valine from 3-methylbutanoic acid.

Accepted Answer

1. Br₂, PBr

Question 17

Bradykinin is a nonapeptide released by globulins in the blood in response to a wasp sting. Hydrolysis gives the following amino acids: 2 Arg, Gly, 2 Phe, 3 Pro, and Ser. Edman degradation gives phenylthiohydantoin of Arg. Cleavage with carboxypeptidase gives Arg. Partial hydrolysis gives the following di- and tripeptides: Phe-Ser, Pro-Gly-Phe, Pro-Pro, Ser-Pro-Phe, Phe-Arg, and Arg-Pro. What is the amino acid sequence of bradykinin?

Accepted Answer

Arg-Pro-Pr

Question 18

Which of the following reagents can be used to convert disulfide bridges into cysteic acid residues?

Accepted Answer

A)  HCO3H  
B)  Zn, HCl 
C)  PhNCS 
D)  PhCH2OCOCl 
E)  CH3I  
A)  HCO3H  
B)  Zn, HCl 
C)  PhNCS 
D)  PhCH2OCOCl 
E)  CH3I

Question 19

________ of a protein usually results in the precipitation of the protein and loss of its biological activity.

Accepted Answer

The answer of ________ of a protein usually results in...

Question 20

Which of the following reagents are commonly used to acylate the amino group of an amino acid?

Accepted Answer

A)  both acetic anhydride and benzyl chloroformate 
B)  both benzyl chloroformate and α-bromoacetic acid 
C)  both α-bromoacetic acid and tosyl chloride 
D)  both tosyl chloride and acetic anhydride 
E)  both benzyl chloroformate and tosyl chloride 
A)  both acetic anhydride and benzyl chloroformate 
B)  both benzyl chloroformate and α-bromoacetic acid 
C)  both α-bromoacetic acid and tosyl chloride 
D)  both tosyl chloride and acetic anhydride 
E)  both benzyl chloroformate and tosyl chloride

Exam 24: Amino Acids, Peptides, and Proteins

Provide a structure of the dipeptide Ser-Gly-Asp at biological pH.

Which amino acid's side chain is negatively charged at biological pH?

Provide the structure of the predominant form of L-methionine present in an aqueous solution at biological pH.

What is the one letter symbol of the amino acid below?

What is the name of the amino acid produced when propanoic acid is subjected to the following sequence of reagents: 1. PBr3, Br2; 2. H2O; 3. NH3, Δ?

Draw the Fischer projection of L-glutamic acid at a pH of 2.

Provide the major organic product in the reaction of L-methionine with benzyl chloroformate.

Provide the structure of the predominant form of L-valine present in an aqueous solution at biological pH.

Which of the following amino acids has a nonpolar side chain?

Amides are:

If the side chain of asparagine is hydrolyzed, what amino acid is formed?

Which of the following arrangements is usually not found in the secondary structure of proteins?

Which of the following amino acids has a side chain which contains a nonbasic nitrogen?

When a disulfide linkage is formed, the compound containing this new linkage has been ________.

Provide a structure of the dipeptide Gly-Asp-Leu at biological pH.

Provide a synthesis of racemic valine from 3-methylbutanoic acid.

Which of the following reagents can be used to convert disulfide bridges into cysteic acid residues?

________ of a protein usually results in the precipitation of the protein and loss of its biological activity.

Which of the following reagents are commonly used to acylate the amino group of an amino acid?

Introduction and Review

Structure and Properties of Organic Molecules

Structure and Stereochemistry of Alkanes

The Study of Chemical Reactions

Stereochemistry

Alkyl Halides: Nucleophilic Substitution and Elimination

Structure and Synthesis of Alkenes

Reactions of Alkenes

Alkynes

Structure and Synthesis of Alcohols

Reactions of Alcohols

Infrared Spectroscopy and Mass Spectrometry

Nuclear Magnetic Resonance Spectroscopy

Ethers, Epoxides, and Thioethers

Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy

Aromatic Compounds

Reactions of Aromatic Compounds

Ketones and Aldehydes

Amines

Carboxylic Acids

Carboxylic Acid Derivatives

Condensations and Alpha Substitutions of Carboxyl Compounds

Carbohydrates and Nucleic Acids

Lipids

Synthetic Polymers

Filters

What is the name of the amino acid produced when propanoic acid is subjected to the following sequence of reagents: 1. PBr₃, Br₂; 2. H₂O; 3. NH₃, Δ?

^{Which of the following arrang}^{ements is usually}^not found in the secondary structure of proteins?