BCH403 Exam Questions| Already
Answered| GRADED A+
E1: A biochemical reaction, without a catalyst or thermodynamic coupling, takes 50 years to reach a
state of equilibrium. Without more information, we cannot make a determination on either the value of
Keq constant or the positive or negative value of the deltaG of the reaction. - ANSWER-FALSE
E1: Due to its small size, the amino acid glycine can be found in tight turns in a protein structure -
ANSWER-TRUE
E1: The deltaG of a reaction is defined as the energy required to bring the concentration of the reactants
and products to equal concentration. - ANSWER-FALSE
E1: One strength of nuclear magnetic resonance spectroscopy is that it can detect multiple
conformations of proteins and one of its limitations is that proteins must contain certain isotopes. -
ANSWER-TRUE
E1: A single residue mutation to an enzyme decreases its rate constant by one half. This means the
reaction now occurs more slowly. - ANSWER-TRUE
The hydrophobic packing of non-polar residues is thermodynamically favorable because of both the
hydrophobic effect and a larger number of weak van der Waals interactions. - ANSWER-TRUE
E1: The classic experiment in which the protein ribonuclease A is first denatured and reduced, then
refolded, was used to demonstrate the role of aromatic residues in stabilizing covalent disulfide bonds. -
ANSWER-FALSE
E1: One reason that we require myoglobin and hemoglobin to store and transport oxygen is because
oxygen by itself has very poor solubility in water - ANSWER-TRUE
E1: A mutation in myoglobin that changes the distal histidine to an alanine will result in a lower P50 -
ANSWER-FALSE
,E1: The stabililty of an a-helix is partly due to the hydrogen bonding that occurs between the carbonyl
oxygen of one helix and the amide hydrogen of a neighboring a-helix - ANSWER-FALSE
E1: Which of the following statements is true regarding the hydrophobic effect? - ANSWER-Non - Polar
molecules are driven together in order to maximize the entropy of water.
E1: The peptide in question 17 is dissolved into a solution that has a pH of 6.5. Under these conditions
the net charge of the peptide is - ANSWER-+1
E1: A glycine residue is disruptive to the stability of an a-helix or a b-strand because: - ANSWER-It's R-
group is too small to participate in stabilizing interactions with neighboring R - groups
E1: With a pKa of 6.37 the carbonic acid/bicarbonate system serves to buffer changes to the pH of
blood. The acid dissociates as follows:
H2CO3 + H20 <-> HCO3- + H30+
If a solution of 0.5M carbonic acid is adjusted to a pH of 2.5, the primary form of the buffer will be: -
ANSWER-H2CO3
E1: Most nonpolar residues are located on the interior of a protein fold, but are occasionally found on
surfaces where they can mediate protein interactions. The molecular basis of a hypothetical infectious
disease is that a bacterial protein interacts with a human protein by sharing a nonpolar surface. Your
goal as a researcher is to find a way to disrupt this interaction. Which of the following surface mutations
are most likely to disrupt the protein interactions? - ANSWER-Leucine --> Glutamine
E1: You've discovered a new species of rodent living at a very high altitude, where the partial pressure of
oxygen is low. What would you predict regarding the oxygen binding capacity of this new species? -
ANSWER-B and D ( it's hemoglobin will have a very low P50 value & the primary amino acid sequence of
its hemoglobin will not be identical to that of a species living in an oxygen rich atmosphere)
E1: the following peptide is composed of which amino acid sequence
, [Picture of sequence. May insert later] - ANSWER-LKQIFKDIWTIGW
E1: The following sequence of 16 residues represents an Alpha helical stretch in an enzyme from the
bacterium that causes tuberculosis. which of the following is not true regarding the structure of this
Alpha Helix?
QFLRDTANSLLDNLIT - ANSWER-Mutation from the phenylalanine residue to a proline will prevent the
rest of the sequence from forming an Alpha Helix.
E1: The residue sequence of a fibrous protein is shown below. which protein does this sequence likely
correspond to?
MGISQKLYRDVNNAFQSRINYWLS - ANSWER-fibroin
E1: Which of the following is true regarding oxygen binding to one molecule of myoglobin? - ANSWER-B
and C (A histidine is required to hydrogen bond with the bound oxygen thus stabilizing it. & the iron
atom is located outside the plane of the heme when oxygen is not bound)
E1: A chromatography column was used to try to purify a protein that is 10 kilodaltons in size. Some of
the illusion fractions were run on SDS page and are shown below, with the lower numbered fractions
eluting first period based only on this information, what kind of chromatographic column was used it
was the attempt successful? The charges on the gel are shown on the left.
[May insert picture later] - ANSWER-Nickel affinity, and it did work
E1: Your goal is to separate a mixture of the two polypeptides shown below, and obtain purified peptide
one for further study as a neurotransmitter. which purification technique would be most effective and
why?
Peptide 1: MHTRRAPLQAWKKPRADHVL
Peptide 2: MHTDEAPLQAWKDPEADHVLW - ANSWER-Cation exchange, since peptide 1 is more positively
charged and will "stick" to that resin best.
Answered| GRADED A+
E1: A biochemical reaction, without a catalyst or thermodynamic coupling, takes 50 years to reach a
state of equilibrium. Without more information, we cannot make a determination on either the value of
Keq constant or the positive or negative value of the deltaG of the reaction. - ANSWER-FALSE
E1: Due to its small size, the amino acid glycine can be found in tight turns in a protein structure -
ANSWER-TRUE
E1: The deltaG of a reaction is defined as the energy required to bring the concentration of the reactants
and products to equal concentration. - ANSWER-FALSE
E1: One strength of nuclear magnetic resonance spectroscopy is that it can detect multiple
conformations of proteins and one of its limitations is that proteins must contain certain isotopes. -
ANSWER-TRUE
E1: A single residue mutation to an enzyme decreases its rate constant by one half. This means the
reaction now occurs more slowly. - ANSWER-TRUE
The hydrophobic packing of non-polar residues is thermodynamically favorable because of both the
hydrophobic effect and a larger number of weak van der Waals interactions. - ANSWER-TRUE
E1: The classic experiment in which the protein ribonuclease A is first denatured and reduced, then
refolded, was used to demonstrate the role of aromatic residues in stabilizing covalent disulfide bonds. -
ANSWER-FALSE
E1: One reason that we require myoglobin and hemoglobin to store and transport oxygen is because
oxygen by itself has very poor solubility in water - ANSWER-TRUE
E1: A mutation in myoglobin that changes the distal histidine to an alanine will result in a lower P50 -
ANSWER-FALSE
,E1: The stabililty of an a-helix is partly due to the hydrogen bonding that occurs between the carbonyl
oxygen of one helix and the amide hydrogen of a neighboring a-helix - ANSWER-FALSE
E1: Which of the following statements is true regarding the hydrophobic effect? - ANSWER-Non - Polar
molecules are driven together in order to maximize the entropy of water.
E1: The peptide in question 17 is dissolved into a solution that has a pH of 6.5. Under these conditions
the net charge of the peptide is - ANSWER-+1
E1: A glycine residue is disruptive to the stability of an a-helix or a b-strand because: - ANSWER-It's R-
group is too small to participate in stabilizing interactions with neighboring R - groups
E1: With a pKa of 6.37 the carbonic acid/bicarbonate system serves to buffer changes to the pH of
blood. The acid dissociates as follows:
H2CO3 + H20 <-> HCO3- + H30+
If a solution of 0.5M carbonic acid is adjusted to a pH of 2.5, the primary form of the buffer will be: -
ANSWER-H2CO3
E1: Most nonpolar residues are located on the interior of a protein fold, but are occasionally found on
surfaces where they can mediate protein interactions. The molecular basis of a hypothetical infectious
disease is that a bacterial protein interacts with a human protein by sharing a nonpolar surface. Your
goal as a researcher is to find a way to disrupt this interaction. Which of the following surface mutations
are most likely to disrupt the protein interactions? - ANSWER-Leucine --> Glutamine
E1: You've discovered a new species of rodent living at a very high altitude, where the partial pressure of
oxygen is low. What would you predict regarding the oxygen binding capacity of this new species? -
ANSWER-B and D ( it's hemoglobin will have a very low P50 value & the primary amino acid sequence of
its hemoglobin will not be identical to that of a species living in an oxygen rich atmosphere)
E1: the following peptide is composed of which amino acid sequence
, [Picture of sequence. May insert later] - ANSWER-LKQIFKDIWTIGW
E1: The following sequence of 16 residues represents an Alpha helical stretch in an enzyme from the
bacterium that causes tuberculosis. which of the following is not true regarding the structure of this
Alpha Helix?
QFLRDTANSLLDNLIT - ANSWER-Mutation from the phenylalanine residue to a proline will prevent the
rest of the sequence from forming an Alpha Helix.
E1: The residue sequence of a fibrous protein is shown below. which protein does this sequence likely
correspond to?
MGISQKLYRDVNNAFQSRINYWLS - ANSWER-fibroin
E1: Which of the following is true regarding oxygen binding to one molecule of myoglobin? - ANSWER-B
and C (A histidine is required to hydrogen bond with the bound oxygen thus stabilizing it. & the iron
atom is located outside the plane of the heme when oxygen is not bound)
E1: A chromatography column was used to try to purify a protein that is 10 kilodaltons in size. Some of
the illusion fractions were run on SDS page and are shown below, with the lower numbered fractions
eluting first period based only on this information, what kind of chromatographic column was used it
was the attempt successful? The charges on the gel are shown on the left.
[May insert picture later] - ANSWER-Nickel affinity, and it did work
E1: Your goal is to separate a mixture of the two polypeptides shown below, and obtain purified peptide
one for further study as a neurotransmitter. which purification technique would be most effective and
why?
Peptide 1: MHTRRAPLQAWKKPRADHVL
Peptide 2: MHTDEAPLQAWKDPEADHVLW - ANSWER-Cation exchange, since peptide 1 is more positively
charged and will "stick" to that resin best.
