Question 1

The net charge on the amino acid cys in a solution at pH 7 is closest to

Accepted Answer

A)  − 2 
B)  − 1. 
C)  0. 
D)  +1. 
A)  − 2 
B)  − 1. 
C)  0. 
D)  +1.

Question 2

The amino and carboxyl groups of amino acids are bonded to which carbon?

Accepted Answer

A)  Both are bonded to the α -carbon. 
B)  Both are bonded to the β -carbon. 
C)  The amino is bonded to the α -carbon, and the carboxyl is bonded to the β -carbon. 
D)  The amino is bonded to the β -carbon, and the carboxyl is bonded to the α -carbon. 
A)  Both are bonded to the α -carbon. 
B)  Both are bonded to the β -carbon. 
C)  The amino is bonded to the α -carbon, and the carboxyl is bonded to the β -carbon. 
D)  The amino is bonded to the β -carbon, and the carboxyl is bonded to the α -carbon.

Question 3

Exhibit 3A (for this chapter)  
Refer to Exhibit 3A. Which of these amino acids could act as a good buffer at pH = 4.5

Accepted Answer

A)  Alanine 
B)  Arginine 
C)  Asparagine 
D)  Cysteine 
E)  Aspartic Acid 
A)  Alanine 
B)  Arginine 
C)  Asparagine 
D)  Cysteine 
E)  Aspartic Acid

Question 4

Exhibit 3B A titration curve.   Refer to Exhibit 3B. The point labeled #1 represents:

Accepted Answer

A)  The fully protonated form 
B)  The pH with maximum negative charge 
C)  The end point of titration with base (OH − ) 
D)  The pI of the amino acid 
E)  None of these 
A)  The fully protonated form 
B)  The pH with maximum negative charge 
C)  The end point of titration with base (OH − ) 
D)  The pI of the amino acid 
E)  None of these

Question 5

Which is a correct pair of abbreviations for an amino acid?

Accepted Answer

A)  Gln \ N 
B)  Tyr \ T 
C)  Asn \ N 
D)  Phe \ P 
E)  Pro \ Q 
A)  Gln \ N 
B)  Tyr \ T 
C)  Asn \ N 
D)  Phe \ P 
E)  Pro \ Q

Question 6

The pKa values of the alpha carboxyl groups of common amino acids are around

Accepted Answer

A)  pH 2 
B)  pH 5 
C)  pH 7 
D)  pH 9 
A)  pH 2 
B)  pH 5 
C)  pH 7 
D)  pH 9

Question 7

Which of the following is NOT a correct combination of an amino acid, its three-letter designation, and its one-letter designation?

Accepted Answer

A)  Lysine, lys, L 
B)  Glycine, gly, G 
C)  Histidine, his, H 
D)  Tryptophan, Trp, W 
E)  Arginine, arg, R 
A)  Lysine, lys, L 
B)  Glycine, gly, G 
C)  Histidine, his, H 
D)  Tryptophan, Trp, W 
E)  Arginine, arg, R

Question 8

Which group consists only of amino acids with basic side chains?

Accepted Answer

A)  leucine and lysine 
B)  arginine and leucine 
C)  lysine and arginine 
D)  arginine and isoleucine 
A)  leucine and lysine 
B)  arginine and leucine 
C)  lysine and arginine 
D)  arginine and isoleucine

Question 9

The pKa values of the side chains of the common amino acids

Accepted Answer

A)  are always at low pH 
B)  are always at high pH 
C)  depend on the chemical nature of the side chain 
D)  are not known 
A)  are always at low pH 
B)  are always at high pH 
C)  depend on the chemical nature of the side chain 
D)  are not known

Question 10

Which amino acids contain sulfur?

Accepted Answer

A)  cysteine and lysine 
B)  cysteine and methionine 
C)  arginine and methionine 
D)  cysteine and isoleucine 
A)  cysteine and lysine 
B)  cysteine and methionine 
C)  arginine and methionine 
D)  cysteine and isoleucine

Question 11

The amino acids which occur in proteins

Accepted Answer

A)  are all of the L- form. 
B)  are all of the D- form. 
C)  can be either the L- or D- form. 
D)  do not have L- and D- forms. 
A)  are all of the L- form. 
B)  are all of the D- form. 
C)  can be either the L- or D- form. 
D)  do not have L- and D- forms.

Question 12

The net charge on the peptide abbreviated CAKE in a solution at pH 7 is closest to

Accepted Answer

A)  − 2 
B)  − 1. 
C)  0. 
D)  +1. 
A)  − 2 
B)  − 1. 
C)  0. 
D)  +1.

Question 13

Which amino acid takes on a positive charge when the R-group gains a proton?

Accepted Answer

A)  Glutamic Acid 
B)  Histidine 
C)  Glutamine 
D)  Tyrosine 
E)  Glycine 
A)  Glutamic Acid 
B)  Histidine 
C)  Glutamine 
D)  Tyrosine 
E)  Glycine

Question 14

Which of the following is true about oxytocin?

Accepted Answer

A)  it is a peptide hormone 
B)  during pregnancy the number of receptors for oxytocin increases 
C)  it is involved in stimulating the flow of milk during nursing 
D)  all of the choices 
A)  it is a peptide hormone 
B)  during pregnancy the number of receptors for oxytocin increases 
C)  it is involved in stimulating the flow of milk during nursing 
D)  all of the choices

Question 15

Oxytocin and vasopressin

Accepted Answer

A)  differ from each other by a single amino acid 
B)  do not contain sulfur 
C)  are peptide hormones 
D)  are tripeptides 
A)  differ from each other by a single amino acid 
B)  do not contain sulfur 
C)  are peptide hormones 
D)  are tripeptides

Question 16

Asp and Glu both have amides as side chains.

Accepted Answer

A) True 
 B)False

Question 17

Which groups of a pair of amino acids must react to form a peptide bond?

Accepted Answer

A)  the two carboxyls 
B)  the two aminos 
C)  the two R-groups 
D)  the carboxyl of one and the amino of the other 
A)  the two carboxyls 
B)  the two aminos 
C)  the two R-groups 
D)  the carboxyl of one and the amino of the other

Question 18

At its isolectric pH, glycine will have

Accepted Answer

A)  both of its ionizable functional groups dissociated. 
B)  neither of its ionizable functional groups dissociated. 
C)  only its carboxyl group dissociated. 
D)  only its amino group dissociated. 
A)  both of its ionizable functional groups dissociated. 
B)  neither of its ionizable functional groups dissociated. 
C)  only its carboxyl group dissociated. 
D)  only its amino group dissociated.

Question 19

This amino acid displays a free amino group in the peptide ALA-GLN-ARG-SER-HIS:

Accepted Answer

A)  ALA 
B)  GLN 
C)  SER 
D)  HIS 
A)  ALA 
B)  GLN 
C)  SER 
D)  HIS

Question 20

Which is the correct one-letter designation for tryptophan?

Accepted Answer

A)  E 
B)  T 
C)  W 
D)  Q 
E)  none of the choices 
A)  E 
B)  T 
C)  W 
D)  Q 
E)  none of the choices

Exam 3: Amino Acids and Peptides

The net charge on the amino acid cys in a solution at pH 7 is closest to

The amino and carboxyl groups of amino acids are bonded to which carbon?

Exhibit 3A (for this chapter) Refer to Exhibit 3A. Which of these amino acids could act as a good buffer at pH = 4.5

Exhibit 3B A titration curve. Refer to Exhibit 3B. The point labeled #1 represents:

Which is a correct pair of abbreviations for an amino acid?

The pKa values of the alpha carboxyl groups of common amino acids are around

Which of the following is NOT a correct combination of an amino acid, its three-letter designation, and its one-letter designation?

Which group consists only of amino acids with basic side chains?

The pKa values of the side chains of the common amino acids

Which amino acids contain sulfur?

The amino acids which occur in proteins

The net charge on the peptide abbreviated CAKE in a solution at pH 7 is closest to

Which amino acid takes on a positive charge when the R-group gains a proton?

Which of the following is true about oxytocin?

Oxytocin and vasopressin

Asp and Glu both have amides as side chains.

Which groups of a pair of amino acids must react to form a peptide bond?

At its isolectric pH, glycine will have

This amino acid displays a free amino group in the peptide ALA-GLN-ARG-SER-HIS:

Which is the correct one-letter designation for tryptophan?

Biochemistry and the Organization of Cells

Water the Solvent for Biochemical Reactions

The Three Dimensional Structure of Proteins

Protein Purification and Characterization Techniques

The Behavior of Proteins Enzymes

The Behavior of Proteins Enzymes Mechanisms and Control

Lipids and Proteins Are Associated in Biological Membranes

Nucleic Acids How Structure Conveys Information

Biosynthesis of Nucleic Acids Replication

Transcription of the Genetic Code the Biosynthesis of Rna

Protein Synthesis Translation of the Genetic Message

Nucleic Acid Biotechnology Techniques

Viruses Cancer and Immunology

The Importance of Energy Changes and Electron Transfer in Metabolism

Carbohydrates

Glycolysis

Storage Mechanisms and Control in Carbohydrate Metabolism

The Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Lipid Metabolism

Photosynthesis

The Metabolism of Nitrogen

Integration of Metabolism Cellular Signaling

Filters

The pK_a values of the alpha carboxyl groups of common amino acids are around

The pK_a values of the side chains of the common amino acids