UNE Medical Biochemistry Midterm Questions With
Complete Solutions.
Which of the following proteins is likely to have quaternary structure?
A multimeric protein that contains multiple peptide chains
Prosthetic groups are complex nonprotein molecules that participate in catalysis
by providing functional groups that form a covalent intermediate between the
enzyme and the substrate. Which of the following is an example of a coenzyme or
cofactor that participates in a covalent catalysis reaction?
Pyridoxal phosphate
Which of the following best describes a protein domain?
A section of a protein structure sufficient to perform a particular chemical or physical
task
Cleavage of fructose 1,6 bisphosphate to dihydroxyacetone and Glyceraldehyde
3-phosphate involves the breaking of a carbon-carbon bond through a process
other than oxidation or hydrolysis. This is achieved by what class of enzymes?
Lyase
A 55-year old man is brought to the emergency room with a chief complaint of
chest pain and tingling in his left arm. Elevation of which of the following
enzymes in circulation would be most indicative of myocardial infarction?
Troponin
Allosteric activators of hemoglobin will increase substrate binding through which
of the following mechanisms?
Binding the protein, and keeping it in the "R" conformation
Which of the following best describes tertiary structure?
Interactions between alpha helices and beta sheets to form a domain
How do most enzymes reduce the activation energy needed to move a reaction
forward?
providing an active site most complementary to the transition state
Domains are common structural elements that retain a particular function within
the protein. Which of the following is an example of a protein domain?
An arrangement of beta-strands connected by alpha-helices (beta-alpha-beta-alpha)
Which amino acid would not be commonly found in the middle of an alpha-helical
domain?
Proline
Which of the following is a true statement with regards to the malate-aspartate
shuttle system?
Generates 2.5 molecules of ATP in mitochondria per each NADH from glycolysis.
Complex II (Succinate Q-reductase) is not considered part of the process of
oxidative phosphorylation because it is unable to do which of the following
activities?
Pump protons from the mitochondrial matrix into the inter membrane space.
Succinate is a substrate for which complex in the electron transport chain?
Complex II (Succinate-Q reductase)
, The glycerophosphate shuttle is the major shuttle of most tissues. Which of the
following best describes the transfer of electrons by this shuttle?
Electrons are directly transferred from glycerol 3-phosphate to an FAD containing
glycerol phosphate dehydrogenase.
A 19-year old male is being evaluated for muscle weakness. Evaluation of a
muscle biopsy revealed normal rates of succinate oxidation but very low rates of
pyruvate oxidation. Further testing determined normal levels of enzymatic activity
in both malate dehydrogenase and pyruvate dehydrogenase. Based on this data,
the patient may have a mutation in a gene encoding for which mitochondrial
protein?
Complex I (NADH Q-oxidoreductase)
Which of the following components of the electron transport chain passes
electrons to O2 causing it to be reduced to H2O?
Cytochrome c oxidase
As electrons flow through complexes in the inner mitochondrial membrane,
protons are pumped from the matrix into the inter membrane space. Which of the
following statements is most reflective of the pH in the inter membrane space?
The pH is higher in the matrix when compared to the intermembrane space.
The malate-aspartate shuttle is used to move reducing equivalents o cytosolic
NADH into the mitochondria where it can be oxidized. Which of the following
compounds is used to move the reducing equivalents from cytosolic NADH into
the mitochondria?
Malate
ATP is a high energy molecule that is often hydrolyzed during reactions. The
energy within ATP is stored primarily in which of the following components of the
molecule?
In the high energy phosphate bonds
Which of the following is an example of enzyme regulation through covalent
modification?
phosphorylation of muscle glycogen phosphorylase
Under low energy conditions, AMP will bind to phosphofructokinase I and
glycogen phosphorylase at site unique to the active site. This enhances the
activity of these enzymes. This is an example of which of the following types of
enzyme regulation?
Allosteric activation
A 28 year old male is recently diagnosed with HIV. As part of his treatment he is
prescribed Nevirapine which interferes with retroviral reverse transcript erase
enzyme. Use the graph below, which of the following best describes the impact of
this drug on its target?
It reduces the catalytic activity of the enzyme.
In the image below, the blue line indicates enzyme kinetics with no inhibitor
present. Based on this information which of the following is true?
The green line shows enzyme kinetics with the addition of a noncompetitive inhibitor.
The association DNA and histones can be modified by histone acetylation. A
decrease in histone acetylation will have which of the following impacts on the
association of DNA and histones?
Complete Solutions.
Which of the following proteins is likely to have quaternary structure?
A multimeric protein that contains multiple peptide chains
Prosthetic groups are complex nonprotein molecules that participate in catalysis
by providing functional groups that form a covalent intermediate between the
enzyme and the substrate. Which of the following is an example of a coenzyme or
cofactor that participates in a covalent catalysis reaction?
Pyridoxal phosphate
Which of the following best describes a protein domain?
A section of a protein structure sufficient to perform a particular chemical or physical
task
Cleavage of fructose 1,6 bisphosphate to dihydroxyacetone and Glyceraldehyde
3-phosphate involves the breaking of a carbon-carbon bond through a process
other than oxidation or hydrolysis. This is achieved by what class of enzymes?
Lyase
A 55-year old man is brought to the emergency room with a chief complaint of
chest pain and tingling in his left arm. Elevation of which of the following
enzymes in circulation would be most indicative of myocardial infarction?
Troponin
Allosteric activators of hemoglobin will increase substrate binding through which
of the following mechanisms?
Binding the protein, and keeping it in the "R" conformation
Which of the following best describes tertiary structure?
Interactions between alpha helices and beta sheets to form a domain
How do most enzymes reduce the activation energy needed to move a reaction
forward?
providing an active site most complementary to the transition state
Domains are common structural elements that retain a particular function within
the protein. Which of the following is an example of a protein domain?
An arrangement of beta-strands connected by alpha-helices (beta-alpha-beta-alpha)
Which amino acid would not be commonly found in the middle of an alpha-helical
domain?
Proline
Which of the following is a true statement with regards to the malate-aspartate
shuttle system?
Generates 2.5 molecules of ATP in mitochondria per each NADH from glycolysis.
Complex II (Succinate Q-reductase) is not considered part of the process of
oxidative phosphorylation because it is unable to do which of the following
activities?
Pump protons from the mitochondrial matrix into the inter membrane space.
Succinate is a substrate for which complex in the electron transport chain?
Complex II (Succinate-Q reductase)
, The glycerophosphate shuttle is the major shuttle of most tissues. Which of the
following best describes the transfer of electrons by this shuttle?
Electrons are directly transferred from glycerol 3-phosphate to an FAD containing
glycerol phosphate dehydrogenase.
A 19-year old male is being evaluated for muscle weakness. Evaluation of a
muscle biopsy revealed normal rates of succinate oxidation but very low rates of
pyruvate oxidation. Further testing determined normal levels of enzymatic activity
in both malate dehydrogenase and pyruvate dehydrogenase. Based on this data,
the patient may have a mutation in a gene encoding for which mitochondrial
protein?
Complex I (NADH Q-oxidoreductase)
Which of the following components of the electron transport chain passes
electrons to O2 causing it to be reduced to H2O?
Cytochrome c oxidase
As electrons flow through complexes in the inner mitochondrial membrane,
protons are pumped from the matrix into the inter membrane space. Which of the
following statements is most reflective of the pH in the inter membrane space?
The pH is higher in the matrix when compared to the intermembrane space.
The malate-aspartate shuttle is used to move reducing equivalents o cytosolic
NADH into the mitochondria where it can be oxidized. Which of the following
compounds is used to move the reducing equivalents from cytosolic NADH into
the mitochondria?
Malate
ATP is a high energy molecule that is often hydrolyzed during reactions. The
energy within ATP is stored primarily in which of the following components of the
molecule?
In the high energy phosphate bonds
Which of the following is an example of enzyme regulation through covalent
modification?
phosphorylation of muscle glycogen phosphorylase
Under low energy conditions, AMP will bind to phosphofructokinase I and
glycogen phosphorylase at site unique to the active site. This enhances the
activity of these enzymes. This is an example of which of the following types of
enzyme regulation?
Allosteric activation
A 28 year old male is recently diagnosed with HIV. As part of his treatment he is
prescribed Nevirapine which interferes with retroviral reverse transcript erase
enzyme. Use the graph below, which of the following best describes the impact of
this drug on its target?
It reduces the catalytic activity of the enzyme.
In the image below, the blue line indicates enzyme kinetics with no inhibitor
present. Based on this information which of the following is true?
The green line shows enzyme kinetics with the addition of a noncompetitive inhibitor.
The association DNA and histones can be modified by histone acetylation. A
decrease in histone acetylation will have which of the following impacts on the
association of DNA and histones?
