MCB 354 QUIZ 1 UPDATED ACTUAL QUESTIONS AND
CORRECT ANSWERS
Question:
1. S2 Which of the following peptides will have the strongest absorbance at 280 nm?
1. ktwyaarwe
2. lileerarye
3. ppsghpfre
4. kstkwnqre
Answer:
ktwyaarwe
Question:
2. S2 Which statement is false?
1. The electron density within the unit cell is mathematically related to the diffraction pattern via a Fourier
transform.
2. Bragg's Law relates the positions of reflections in a diffraction pattern to the unit cell dimensions.
3. The unit cell is repeated through translational symmetry to build a crystal.
4. The asymmetric unit is the smallest repeating structure that can build a crystal through rotational and
translational symmetry.
5. Proteins within crystals are dehydrated.
Answer:
Proteins within crystals are dehydrated.
Question:
3. S2 What structure will the sequence VKELEDKVEELL- SKNYHLENEVARLKKLV most likely
form?
1. A dimeric coiled-coil
2. A strand in a µ-sandwich domain
3. A fully water-exposed helix
4. A transmembrane α-helix
Answer:
A dimeric coiled-coil
Question:
4. S2 Hydrolysis of the phosphate group from ATP to form ADP has ∆G°' of -31 kJ/mol. Hydrolysis of the
phosphate group from 1,3-bisphosphoglycerate to form 3-phosphoglycerate has ∆G°' of -50 kJ/mol. The
two reactions are coupled by a phosphoryl-transferase enzyme (i.e. a kinase). Under standard conditions, in
which direction will the coupled transfer reaction proceed?
1. Phosphate will be transferred from 1,3-bisphosphoglycerate to ADP.
2. Phosphate will be hydrolyzed from both ATP and 1,3-bisphosphoglycerate.
3. Phosphate will be transferred from ATP to 3-phosphoglycerate.
4. The coupled reaction will be at equilibrium with no net phosphate transfer.
Answer:
Phosphate will be transferred from 1,3-bisphosphoglycerate to ADP.
, Question:
5. S2 Which of the following is not true of a hydrogen bond?
1. It is shorter and stronger than a van der Waals contact.
2. It requires the hydrogen bond acceptor to have an available lone pair of electrons
3. Water makes three hydrogen bonds; one to the oxygen and two to the hydrogens.
4. Hydrogen bonds between atoms within a peptide chain are important for determining 3D structure
5. The strength is dependent on bond angle and length.
6. It involves an electrostatic attraction between a δ+ hydrogen and a δ- electronegative atom.
7. It is longer and weaker than a covalent bond
Answer:
Water makes three hydrogen bonds; one to the oxygen and two to the hydrogens.
Question:
6. S2 The sulfhydryl group of Cys-575 in Taq polymerase has a pKa of 8.47. In a solution of Taq
polymerase, what percentage of all the Cys-575 residues will be deprotonated at pH 9.00?
1) 98.3 %
2) 88.8 %
3) 77.2 %
4) 19.1 %
5) 36.2 %
Answer:
77.2 %
Question:
7. S2 What structure is the amino acid sequence SLTITLEA most likely to form?
1. A fully water-exposed helix
2. A transmembrane α-helix
3. A strand in a µ-sandwich domain
4. A dimeric coiled-coil
Answer:
A strand in a µ-sandwich domain
Question:
8. S2 The cholesterol-lowering drug rosuvastatin inhibits the enzyme HMG-CoA-reductase, which
catalyzes the rate-limiting step in cholesterol biosynthesis. Rosuvastatin binds the enzyme with ∆G°' =
-50.6 kJ / mol at 25.0 °C. What is the KD for the interaction? (R = 8.31 J K-1 mol-1)
1) 7.40 x 108 M
2) 1.35 nM
3) 0.98 M
4) 1.67 µM
Answer:
1.35 nM
CORRECT ANSWERS
Question:
1. S2 Which of the following peptides will have the strongest absorbance at 280 nm?
1. ktwyaarwe
2. lileerarye
3. ppsghpfre
4. kstkwnqre
Answer:
ktwyaarwe
Question:
2. S2 Which statement is false?
1. The electron density within the unit cell is mathematically related to the diffraction pattern via a Fourier
transform.
2. Bragg's Law relates the positions of reflections in a diffraction pattern to the unit cell dimensions.
3. The unit cell is repeated through translational symmetry to build a crystal.
4. The asymmetric unit is the smallest repeating structure that can build a crystal through rotational and
translational symmetry.
5. Proteins within crystals are dehydrated.
Answer:
Proteins within crystals are dehydrated.
Question:
3. S2 What structure will the sequence VKELEDKVEELL- SKNYHLENEVARLKKLV most likely
form?
1. A dimeric coiled-coil
2. A strand in a µ-sandwich domain
3. A fully water-exposed helix
4. A transmembrane α-helix
Answer:
A dimeric coiled-coil
Question:
4. S2 Hydrolysis of the phosphate group from ATP to form ADP has ∆G°' of -31 kJ/mol. Hydrolysis of the
phosphate group from 1,3-bisphosphoglycerate to form 3-phosphoglycerate has ∆G°' of -50 kJ/mol. The
two reactions are coupled by a phosphoryl-transferase enzyme (i.e. a kinase). Under standard conditions, in
which direction will the coupled transfer reaction proceed?
1. Phosphate will be transferred from 1,3-bisphosphoglycerate to ADP.
2. Phosphate will be hydrolyzed from both ATP and 1,3-bisphosphoglycerate.
3. Phosphate will be transferred from ATP to 3-phosphoglycerate.
4. The coupled reaction will be at equilibrium with no net phosphate transfer.
Answer:
Phosphate will be transferred from 1,3-bisphosphoglycerate to ADP.
, Question:
5. S2 Which of the following is not true of a hydrogen bond?
1. It is shorter and stronger than a van der Waals contact.
2. It requires the hydrogen bond acceptor to have an available lone pair of electrons
3. Water makes three hydrogen bonds; one to the oxygen and two to the hydrogens.
4. Hydrogen bonds between atoms within a peptide chain are important for determining 3D structure
5. The strength is dependent on bond angle and length.
6. It involves an electrostatic attraction between a δ+ hydrogen and a δ- electronegative atom.
7. It is longer and weaker than a covalent bond
Answer:
Water makes three hydrogen bonds; one to the oxygen and two to the hydrogens.
Question:
6. S2 The sulfhydryl group of Cys-575 in Taq polymerase has a pKa of 8.47. In a solution of Taq
polymerase, what percentage of all the Cys-575 residues will be deprotonated at pH 9.00?
1) 98.3 %
2) 88.8 %
3) 77.2 %
4) 19.1 %
5) 36.2 %
Answer:
77.2 %
Question:
7. S2 What structure is the amino acid sequence SLTITLEA most likely to form?
1. A fully water-exposed helix
2. A transmembrane α-helix
3. A strand in a µ-sandwich domain
4. A dimeric coiled-coil
Answer:
A strand in a µ-sandwich domain
Question:
8. S2 The cholesterol-lowering drug rosuvastatin inhibits the enzyme HMG-CoA-reductase, which
catalyzes the rate-limiting step in cholesterol biosynthesis. Rosuvastatin binds the enzyme with ∆G°' =
-50.6 kJ / mol at 25.0 °C. What is the KD for the interaction? (R = 8.31 J K-1 mol-1)
1) 7.40 x 108 M
2) 1.35 nM
3) 0.98 M
4) 1.67 µM
Answer:
1.35 nM
