Biochemistry Chapter 4 Test Bank by
Lehninger 2025\2026 Edition.
All of the following are considered "weak" interactions in proteins, except:
A) hydrogen bonds.
B) hydrophobic interactions.
C) ionic bonds.
D) peptide bonds.
E) van der Waals forces. - Answer D) peptide bonds.
The most important contribution to the stability of a protein's conformation appears to be the:
A) entropy increase from the decrease in ordered water molecules forming a solvent shell
around it.
B) maximum entropy increase from ionic interactions between the ionized amino acids in a
protein.
C) sum of free energies of formation of many weak interactions among the hundreds of amino
acids in a protein.
D) sum of free energies of formation of many weak interactions between its polar amino acids
and surrounding water.
E) stabilizing effect of hydrogen bonding between the carbonyl group of one peptide bond and
the amino group of another. - Answer A) entropy increase from the decrease in ordered water
molecules forming a solvent shell around it.
In an aqueous solution, protein conformation is determined by two major factors. One is the
formation of the maximum number of hydrogen bonds. The other is the:
A) formation of the maximum number of hydrophilic interactions.
B) maximization of ionic interactions.
C) minimization of entropy by the formation of a water solvent shell around the protein.
D) placement of hydrophobic amino acid residues within the interior of the protein.
E) placement of polar amino acid residues around the exterior of the protein. - Answer D)
, B) peptide bonds are essentially planar, with no rotation about the C—N axis.
C) peptide bonds in proteins are unusual, and unlike those in small model compounds.
D) peptide bond structure is extraordinarily complex.
E) primary structure of all proteins is similar, although the secondary and tertiary structure may
differ greatly. - Answer B) peptide bonds are essentially planar, with no rotation about the C—
N axis.
In the diagram below, the plane drawn behind the peptide bond indicates the:
A) absence of rotation around the C—N bond because of its partial double-bond character.
B) plane of rotation around the Cα—N bond.
C) region of steric hindrance determined by the large C=O group.
D) region of the peptide bond that contributes to a Ramachandran plot.
E) theoretical space between -180 and +180 degrees that can be occupied by the φ and ψ
angles in the peptide bond. - Answer A) absence of rotation around the C—N bond because of
its partial double-bond character.
Which of the following best represents the backbone arrangement of two peptide bonds?
A) Cα—N—Cα—C—Cα—N—Cα—C
B) Cα—N—C—C—N—Cα
C) C—N—Cα—Cα—C—N
D) Cα—C—N—Cα—C—N
E) Cα—Cα—C—N—Cα—Cα—C - Answer D) Cα—C—N—Cα—C—N
Which of the following pairs of bonds within a peptide backbone show free rotation around
both bonds?
A) Cα—C and N—Cα
B) C=O and N—C
C) C=O and N—Cα
D) N—C and Cα—C
E) N—Cα and N—C - Answer A) Cα—C and N—Cα
Roughly how many amino acids are there in one turn of an α helix?
Lehninger 2025\2026 Edition.
All of the following are considered "weak" interactions in proteins, except:
A) hydrogen bonds.
B) hydrophobic interactions.
C) ionic bonds.
D) peptide bonds.
E) van der Waals forces. - Answer D) peptide bonds.
The most important contribution to the stability of a protein's conformation appears to be the:
A) entropy increase from the decrease in ordered water molecules forming a solvent shell
around it.
B) maximum entropy increase from ionic interactions between the ionized amino acids in a
protein.
C) sum of free energies of formation of many weak interactions among the hundreds of amino
acids in a protein.
D) sum of free energies of formation of many weak interactions between its polar amino acids
and surrounding water.
E) stabilizing effect of hydrogen bonding between the carbonyl group of one peptide bond and
the amino group of another. - Answer A) entropy increase from the decrease in ordered water
molecules forming a solvent shell around it.
In an aqueous solution, protein conformation is determined by two major factors. One is the
formation of the maximum number of hydrogen bonds. The other is the:
A) formation of the maximum number of hydrophilic interactions.
B) maximization of ionic interactions.
C) minimization of entropy by the formation of a water solvent shell around the protein.
D) placement of hydrophobic amino acid residues within the interior of the protein.
E) placement of polar amino acid residues around the exterior of the protein. - Answer D)
, B) peptide bonds are essentially planar, with no rotation about the C—N axis.
C) peptide bonds in proteins are unusual, and unlike those in small model compounds.
D) peptide bond structure is extraordinarily complex.
E) primary structure of all proteins is similar, although the secondary and tertiary structure may
differ greatly. - Answer B) peptide bonds are essentially planar, with no rotation about the C—
N axis.
In the diagram below, the plane drawn behind the peptide bond indicates the:
A) absence of rotation around the C—N bond because of its partial double-bond character.
B) plane of rotation around the Cα—N bond.
C) region of steric hindrance determined by the large C=O group.
D) region of the peptide bond that contributes to a Ramachandran plot.
E) theoretical space between -180 and +180 degrees that can be occupied by the φ and ψ
angles in the peptide bond. - Answer A) absence of rotation around the C—N bond because of
its partial double-bond character.
Which of the following best represents the backbone arrangement of two peptide bonds?
A) Cα—N—Cα—C—Cα—N—Cα—C
B) Cα—N—C—C—N—Cα
C) C—N—Cα—Cα—C—N
D) Cα—C—N—Cα—C—N
E) Cα—Cα—C—N—Cα—Cα—C - Answer D) Cα—C—N—Cα—C—N
Which of the following pairs of bonds within a peptide backbone show free rotation around
both bonds?
A) Cα—C and N—Cα
B) C=O and N—C
C) C=O and N—Cα
D) N—C and Cα—C
E) N—Cα and N—C - Answer A) Cα—C and N—Cα
Roughly how many amino acids are there in one turn of an α helix?
