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UNE CHEM 1005 Midterm Review Exam Questions and Answers
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UNE CHEM 1005 Midterm Review Exam Questions and Answers
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UNE CHEM 1005 Midterm Review ExamQuestions and Answers
An 𝛂-helical arrangment of amino acids is considered to be part of what level of protein
structure? - Answers -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? - Answers -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? - Answers -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? - Answers -Lyase
Which of the following best describes tertiary structure? - Answers -Interactions
between α-helices and β sheets to form a domain
Which of the following best describes a protein domain? - Answers -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? - Answers -folding of the secondary
structures
Chymotrypsin is a protease that cleaves peptide bonds. It is characterized as which of
the following classes of enzymes? - Answers -hydrolase
α-helices and β-sheets are primarily stabilized by which of the following interactions? -
Answers -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? -
Answers -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? - Answers -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? - Answers -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? - Answers -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? -
Answers -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?
- Answers -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? - Answers -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? - Answers -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? - Answers -substrates or ligands that bind the active site
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