UNE CHEM 1005 Midterm Review Questions & Answers
Rated 100% Correct!!
An 𝛂-helical arrangment of amino acids is considered to be part of what level of
protein structure?
secondary structure
Hemoglobin has the ability to display cooperative binding, while myoglobin does
not display this binding kinetic pattern. Which difference between the two
proteins accounts for this difference in binding kinetics?
the presence of quaternary structure in hemoglobin; cooperativity is a binding
characteristic only displayed in proteins with a quaternary structure
A 22y/o female presents to the emergency department with acute abdominal pain.
She indicates the pain came on rapidly in her mid-abdominal region. Laboratory
tests indicate elevated levels of amylase. This result would indicate a dysfunction
with which organ?
Pancreas
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
Which of the following best describes tertiary structure?
Interactions between α-helices and β sheets to form a domain
Which of the following best describes a protein domain?
A section of a protein structure sufficient to perform a particular chemical or physical
task
A 19-year-old boy is diagnosed with Creutzfeldt-Jakob Disease which is caused
by the introduction of an amyloid fold in the disease-causing protein. The
introduction of this fold causes the protein to transition from a primarily α-helical
structure to an aggregate of mostly β-sheets. This change in protein structure
(leading to disease) is best attributed to changes in which of the following?
folding of the secondary structures
Chymotrypsin is a protease that cleaves peptide bonds. It is characterized as
which of the following classes of enzymes?
hydrolase
α-helices and β-sheets are primarily stabilized by which of the following
interactions?
hydrogen bonding
Changes in the physiological variables listed below can alter the affinity of
hemoglobin for oxygen. Which of the following will lower the affinity of
hemoglobin for oxygen?
increase in 2,3 bisphosphoglycerate (BPG)
Activity of an enzyme is increased when the enzyme is phosphorylated on an
exposed tyrosine residue. Phosphorylation of this AA is classified as?
Covalent modification--phosphorylation to an enzyme that can increase/decrease
activity of an enzyme
, Covalent catalysis is used by many enzymes to cleave peptide bonds. All of the
following AA side chains EXCEPT _____ will help reaction?
Tyrosine, histidine and methionine; NOT valine--nonpolar AA that lacks a nucleophile to
facilitate the generation of a catalyst-substrate covalent bond
If a mutation is made within the active site of an enzyme resulting in an increase
in Km, which of the following will be true with respect to the enzyme kinetics?
the enzyme will require a higher substrate concentration to reach 1/2 Vmax
what are the metabolic consequences of changes to the ubiquitin-proteasome
system?
increases protein ubiquitination, would lead to increase in protein degradation -->
decrease in product production OR decrease in protein degradation, leading to
accomulation of the enzyme or protein --> INCREASE in product production
Protein Z requires phosphorylation at an exposed tyrosine residue for activity. If
we modify this tyrosine to a glycine, what impact does this have on the activity of
protein Z?
Loss of the phosphorylation site will reduce the activity of the enzyme (tyrosine has an
exposed hydroxyl group that allows for phosphorylation and glycine doesn't, so
modifying the enzyme to glycine takes away that available phosphorylation site. Loss of
that site will reduce the activity of the enzyme b/c can no longer be phosphorlyzed)
The following represents a series of reactions. As levels of B increase, this will
decrease the conversion of S3 to B. Which of the following best describes this
type of regulation in a biosynthetic pathway?
feedback inhibition
In the image below the blue line indicates enzyme kinetics with no inhibitor
present. Based on this information which of the following is true?
green line shows enzyme kinetics with the addition of a noncompetitive inhibitor
Children with cystinosis have growth delay and both renal and ocular issues due
to accumulation of cysteine in cellular lysosomes. The defect involves a specific
lysosomal membrane receptor that facilitates cysteine removal from the cell. An
effective therapy has been administration of a drug with a similar structure to
cysteine. This therapy reflects the general principle that competitive inhibitors
typically resemble the structure of which of the following?
substrates or ligands that bind the active site
The association of 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?
increase DNA: histone association
An enzyme is participating in a general acid-base catalysis reaction with an
optimal reaction pH of 6.0. If acid is added to the environment reducing the pH to
3, what is the likely impact to the rate of reaction?
the rate of the reaction is likely to decrease as the pH is out of optimal catalytic range
Which of the following is an example of enzyme regulation through covalent
modification?
phosphorylation of muscle glycogen phosphorylase
If a mutation is made within the active site of an enzyme resulting in a decrease in
Km, which of the following will be true with respect to the enzyme kinetics?
Rated 100% Correct!!
An 𝛂-helical arrangment of amino acids is considered to be part of what level of
protein structure?
secondary structure
Hemoglobin has the ability to display cooperative binding, while myoglobin does
not display this binding kinetic pattern. Which difference between the two
proteins accounts for this difference in binding kinetics?
the presence of quaternary structure in hemoglobin; cooperativity is a binding
characteristic only displayed in proteins with a quaternary structure
A 22y/o female presents to the emergency department with acute abdominal pain.
She indicates the pain came on rapidly in her mid-abdominal region. Laboratory
tests indicate elevated levels of amylase. This result would indicate a dysfunction
with which organ?
Pancreas
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
Which of the following best describes tertiary structure?
Interactions between α-helices and β sheets to form a domain
Which of the following best describes a protein domain?
A section of a protein structure sufficient to perform a particular chemical or physical
task
A 19-year-old boy is diagnosed with Creutzfeldt-Jakob Disease which is caused
by the introduction of an amyloid fold in the disease-causing protein. The
introduction of this fold causes the protein to transition from a primarily α-helical
structure to an aggregate of mostly β-sheets. This change in protein structure
(leading to disease) is best attributed to changes in which of the following?
folding of the secondary structures
Chymotrypsin is a protease that cleaves peptide bonds. It is characterized as
which of the following classes of enzymes?
hydrolase
α-helices and β-sheets are primarily stabilized by which of the following
interactions?
hydrogen bonding
Changes in the physiological variables listed below can alter the affinity of
hemoglobin for oxygen. Which of the following will lower the affinity of
hemoglobin for oxygen?
increase in 2,3 bisphosphoglycerate (BPG)
Activity of an enzyme is increased when the enzyme is phosphorylated on an
exposed tyrosine residue. Phosphorylation of this AA is classified as?
Covalent modification--phosphorylation to an enzyme that can increase/decrease
activity of an enzyme
, Covalent catalysis is used by many enzymes to cleave peptide bonds. All of the
following AA side chains EXCEPT _____ will help reaction?
Tyrosine, histidine and methionine; NOT valine--nonpolar AA that lacks a nucleophile to
facilitate the generation of a catalyst-substrate covalent bond
If a mutation is made within the active site of an enzyme resulting in an increase
in Km, which of the following will be true with respect to the enzyme kinetics?
the enzyme will require a higher substrate concentration to reach 1/2 Vmax
what are the metabolic consequences of changes to the ubiquitin-proteasome
system?
increases protein ubiquitination, would lead to increase in protein degradation -->
decrease in product production OR decrease in protein degradation, leading to
accomulation of the enzyme or protein --> INCREASE in product production
Protein Z requires phosphorylation at an exposed tyrosine residue for activity. If
we modify this tyrosine to a glycine, what impact does this have on the activity of
protein Z?
Loss of the phosphorylation site will reduce the activity of the enzyme (tyrosine has an
exposed hydroxyl group that allows for phosphorylation and glycine doesn't, so
modifying the enzyme to glycine takes away that available phosphorylation site. Loss of
that site will reduce the activity of the enzyme b/c can no longer be phosphorlyzed)
The following represents a series of reactions. As levels of B increase, this will
decrease the conversion of S3 to B. Which of the following best describes this
type of regulation in a biosynthetic pathway?
feedback inhibition
In the image below the blue line indicates enzyme kinetics with no inhibitor
present. Based on this information which of the following is true?
green line shows enzyme kinetics with the addition of a noncompetitive inhibitor
Children with cystinosis have growth delay and both renal and ocular issues due
to accumulation of cysteine in cellular lysosomes. The defect involves a specific
lysosomal membrane receptor that facilitates cysteine removal from the cell. An
effective therapy has been administration of a drug with a similar structure to
cysteine. This therapy reflects the general principle that competitive inhibitors
typically resemble the structure of which of the following?
substrates or ligands that bind the active site
The association of 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?
increase DNA: histone association
An enzyme is participating in a general acid-base catalysis reaction with an
optimal reaction pH of 6.0. If acid is added to the environment reducing the pH to
3, what is the likely impact to the rate of reaction?
the rate of the reaction is likely to decrease as the pH is out of optimal catalytic range
Which of the following is an example of enzyme regulation through covalent
modification?
phosphorylation of muscle glycogen phosphorylase
If a mutation is made within the active site of an enzyme resulting in a decrease in
Km, which of the following will be true with respect to the enzyme kinetics?
