Lehninger Principles of Biochemistry (7th edition)
Questions and Answers ( Chapter 3, 4, and 5)
Which of the following pairs of bonds within a peptide backbone show free rotation around both bonds?
A) C = O and N - C
B) C = O and N - Cn
C) Cα - C and N - Cα
D) N - C and Cα - C
E) N - Cα and N - C ANSW - D) N - C and Cα - C
Thr and/or Leu residues tend to disrupt an α helix when they occur next to each other in a protein
because:
A) Steric hindrance occurs between the bulky The side chains
B) An amino acid like Thr is highly hydrophobic
C) Covalent interactions may occur between the Thr side chains
D) Electrostatic repulsion occurs between the Thr side chains
E) The R group of Thr can form a hydrogen bond ANSW - A) Steric hindrance occurs between the bulky
The side chains
The α-keratin chains indicated by the diagram below have undergone one chemical step. To alter the
shape of the α-keratin chains -- as in hair waving -- what subsequent steps are required?
A) Chemical oxidation and then shape remodeling
B) Shape remodeling and then chemical oxidation
C) Chemical reduction and then chemical oxidation
D) Chemical reduction and then shape remodeling
E) Shape remodeling and then chemical reduction ANSW - B) Shape remodeling and chemical oxidation
Determining the precise spacing of atoms within a large protein is possible only through the use of:
A) X-ray diffraction
, B) Electron Microscopy
C) Light Microscopy
D) Molecular model building
E) Ramachandran plots ANSW - A) X-ray diffraction
Which of the following is LEAST likely to result in protein denaturation?
A) Altering net charge by changing pH
B) Disruption of weak interactions by boiling
C) Changing the salt concentration
D) Exposure to detergents
E) Micing with organic solvents such as acetone ANSW - B) Changing the salt concentration
Protein S will fold into its native conformation only when protein Q is also present in the solution.
However, protein Q can fold into its native conformation without protein S. Protein Q, therefore, may
function as a ____________ for protein S.
A) Ligand
B) Protein Precursor
C) Molecular chaperone
D) Structural Motif
E) Super secondary structural unit ANSW - C) Molecular chaperone
Which of the following statements concerning proteins is true?
A) They are a form of secondary structure
B) They are examples of structural motifs
C) They consist of separate polypeptide chains (subunits)
D) They have been found only in prokaryotic proteins
E) They may retain their correct shape even when separated from the rest of the protein ANSW - E) They
may retain their correct shape even when separated from the rest of the protein
What important function do molecular chaperones perform?
Questions and Answers ( Chapter 3, 4, and 5)
Which of the following pairs of bonds within a peptide backbone show free rotation around both bonds?
A) C = O and N - C
B) C = O and N - Cn
C) Cα - C and N - Cα
D) N - C and Cα - C
E) N - Cα and N - C ANSW - D) N - C and Cα - C
Thr and/or Leu residues tend to disrupt an α helix when they occur next to each other in a protein
because:
A) Steric hindrance occurs between the bulky The side chains
B) An amino acid like Thr is highly hydrophobic
C) Covalent interactions may occur between the Thr side chains
D) Electrostatic repulsion occurs between the Thr side chains
E) The R group of Thr can form a hydrogen bond ANSW - A) Steric hindrance occurs between the bulky
The side chains
The α-keratin chains indicated by the diagram below have undergone one chemical step. To alter the
shape of the α-keratin chains -- as in hair waving -- what subsequent steps are required?
A) Chemical oxidation and then shape remodeling
B) Shape remodeling and then chemical oxidation
C) Chemical reduction and then chemical oxidation
D) Chemical reduction and then shape remodeling
E) Shape remodeling and then chemical reduction ANSW - B) Shape remodeling and chemical oxidation
Determining the precise spacing of atoms within a large protein is possible only through the use of:
A) X-ray diffraction
, B) Electron Microscopy
C) Light Microscopy
D) Molecular model building
E) Ramachandran plots ANSW - A) X-ray diffraction
Which of the following is LEAST likely to result in protein denaturation?
A) Altering net charge by changing pH
B) Disruption of weak interactions by boiling
C) Changing the salt concentration
D) Exposure to detergents
E) Micing with organic solvents such as acetone ANSW - B) Changing the salt concentration
Protein S will fold into its native conformation only when protein Q is also present in the solution.
However, protein Q can fold into its native conformation without protein S. Protein Q, therefore, may
function as a ____________ for protein S.
A) Ligand
B) Protein Precursor
C) Molecular chaperone
D) Structural Motif
E) Super secondary structural unit ANSW - C) Molecular chaperone
Which of the following statements concerning proteins is true?
A) They are a form of secondary structure
B) They are examples of structural motifs
C) They consist of separate polypeptide chains (subunits)
D) They have been found only in prokaryotic proteins
E) They may retain their correct shape even when separated from the rest of the protein ANSW - E) They
may retain their correct shape even when separated from the rest of the protein
What important function do molecular chaperones perform?
