Download 1 Old Exam I Questions Choose an answer of A,B, C, or D for each

Old Exam I Questions
Choose an answer of A,B, C, or D for each of the following Multiple Choice Questions 1-30.
Give your answer on the computer grid sheet AND in this exam booklet. (2 pts. ea.)
1) Which of the following statements describes a covalent bond between Carbon and
Hydrogen: pg 14, 15
A) The electrons are shared equally between the two atoms of the bond.
B) The electrons of the bond are pulled closer to the nucleus of Hydrogen, because its outer
shell electron is closer to its nucleus than the outer shell electrons of Carbon are to its
nucleus.
C) The electrons of the bond are pulled closer to the nucleus of Hydrogen, because its
nucleus contains more protons than Carbon.
D) The electrons of the bond are pulled slightly closer to the nucleus of Carbon, because
although its outer shell electrons are located farther away from the protons of its nucleus,
it contains more protons than Hydrogen. X
2) Which of the following is a TRUE statement about ionic bonds in protein structure: pg 19,
21, 27, 28
A) Ionic bonds on the external surface of the folded protein are more stable than those buried
in the protein interior.
B) In an ionic bond, a hydrogen atom carrying a partial positive charge on the electronegative
atom of one covalent bond interacts with the partial negative charge of an electronegative
atom of a second polar covalent bond.
C) Ionic bonds can only form between acidic and basic polar charged amino acid R groups in
a specific pH range. X
D) Ionic bonds only exist in inorganic molecules.
3) Which of the following types of non-covalent bonds or interactions is thought to be primarily
responsible for driving the three dimensional folding of a protein: pg 29
A) Ionic bonds
B) Hydrogen bonds
C) Van der Waals Interactions
D) Hydrophobic Interactions X
4) Which of the following types of non-covalent bonds or interactions is responsible for forming
the α helix and β sheet secondary structural motifs of a protein: pg 23-25
A) Ionic bonds between polar charged amino acid R groups
B) Hydrogen bonds between electronegative atoms of polar uncharged amino acid R groups
C) Hydrogen bonds between electronegative atoms of the peptide bond X
D) Hydrophobic Interactions between atoms of the peptide bond
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5) Which of the following ratios of phosphoric acid to its conjugate base would be most likely
to exist in a Phosphate buffered solution at pH 14.0. pg 30
H+
H3PO4
pK'
H+
H2PO4
~ 2.0
pK'
HPO4
~7.0
H+
pK'
PO4
~ 12.0
A) 1 H3PO4 : 1 H2PO4
B) 1 H2PO4 : 1 HPO4
C) 1 HPO4 : 1 PO4,
D) mostly PO4 X
6) Using the Table of pK' values for various polar charged and polar uncharged amino acids,
which of the following pairs of amino acid R groups would be capable of forming an ionic
bond in a protein in a pH 7.0 buffered solution. pg 31
A) Aspartic Acid and Histidine
B) Aspartic Acid and Glutamic Acid
C) Histidine and Arginine
D) Glutamic Acid and Arginine X
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7) Amphipathic alpha-helical regions of proteins can cluster together to form an ion channel
through a plasma membrane (e.g., the K+ channel). Bearing in mind which amino acids are
compatible with forming an alpha helix and the average number of amino acid residues per
helical turn, which of the following polypeptides would be most likely to form an
amphipathic helix in an ion channel. pg 73
Position: 1
2
3
4
5
A)
B)
C)
D)
leu
leu
pro
ala
ile
val
ile
leu
gly
lys
pro
ile
met
leu
val
val
val
ile
leu
leu
6
7
8
leu ile val
val ile arg
lys pro glu
met gly ile
9 10 11 12 13 14 15 16 17
ala gly val leu leu
met phe val lys gly
pro glu asp pro arg
glu lys arg lys lys
leu
val
his
arg
val
leu
val
arg
gly leu
his leu X
pro glu
arg his
8) Which of the following types of bonds or interactions between lipid hydrocarbon tails is
responsible for lipids forming a membrane bilayer or membranous vesicles in water: pg 27,
63
A)
B)
C)
D)
Hydrophobic interactions X
Hydrogen bonding
Ionic interactions
Covalent bonds
9) Which of the following pairs of amino acids would you predict to only participate in Van der
Waals interactions in the three dimensional folding of a protein: pg 20, 22, 29
A)
B)
C)
D)
Asp - Lys
Asp- Glu
Asn - Gln
Val - Ala X
10) Which of the following pairs of amino acids could form a covalent disulfide bond to link two
polypeptides together in a multi-subunit protein complex: pg 18
A)
B)
C)
D)
Glu -His
Cys - Cys X
Ser - Thr
Val - Ala
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11) Which of the following methods would provide the highest resolution image of a specific
protein’s distribution in the lipid bilayer of a plasma membrane: pg 72
A) immunoelectron microscopy X
B) immunofluorescence micrsocopy
C) epifluorescence of the protein fused to GFP
D) electron microscopy
12) Which of the following methods could be used to monitor changes in the location of a
specific protein inside a living cell: pg 6
A) light microscopy
B) immunofluorescence microscopy
C) epifluorescence of the protein fused to GFP X
D) immunoelectron microscopy
13) Which of the following components of the confocal microscope allows the cell biologist to
take an optical section of a thick specimen. not covered
A)
B)
C)
D)
the excitation filter between the light source and specimen
the barrier filter between the specimen and detector
the dichroic mirror between the specimen and detector
the pinhole aperture between the specimen and detector that is confocal to the specific
focal plane of the specimen X
14) Which of the following infectious agents is thought to consist of protein alone: pg 12, 13
A)
B)
C)
D)
Salmonella bacterium
HIV virus
PrPc
PrPsc X
15) Which of the following lipid compositions would you predict to find in the plasma
membrane surrounding a membrane protein found to have a very long FRAP time: pg 71, 68
A)
B)
C)
D)
saturated phospholipids X
de-hydrogenated phospholipids
cis unstaturated phospholipids
low cholesterol throughout the plasma membrane
4
16) Which portion of the lipid molecule diagrammed below (labeled 1, 2, 3, or 4) tells you that
the lipid is a phosphoglyceride: pg 67
A)
B)
C)
D)
3
1
2
3X
4
4
1
2
17) In the diagram of the amino acid below, which of the circled atoms (labeled 1, 2, 3, or 4)
participates in the H bonds responsible for forming the α-helix secondary structural motif:
pg 24
A) 1
1
2
B) 2
C) 3
D) 4 X
3
4
20) Mutations in which of the following membrane transport proteins are responsible for the
disease cystic fibrosis: pg 87, 86, 78, 79
A) H+/K+ ATPase
B) CFTR ABC transporter X
C) Voltage-gated K+ ion channel
D) GLUT 4
21) Mutations in which of the following membrane transport proteins are associated with Type II
diabetes: pg 87, 86, 78, 79
A) H+/K+ ATPase
B) CFTR ABC transporter
C) Voltage-gated K+ ion channel
D) GLUT 4 X
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22) A heterozygous mutation in which of the following membrane transport proteins is thought
to have conferred resistance to cholera infections in European populations: pg 87, 86, 78, 79
A) H+/K+ ATPase
B) CFTR ABC transporter X
C) Voltage-gated K+ ion channel
D) GLUT 4
23) Which of the following membrane transport proteins is the target of the drug Prilosec in
treating acid indigestion: pg 87, 86, 78, 79
A) H+/K+ ATPase X
B) CFTR ABC transporter
C) Voltage-gated K+ ion channel
D) GLUT 4
24) The effect of nerve gas on skeletal muscle is: pg 83
A)
B)
C)
D)
Continued contraction due to inhibition of acetylcholine destruction X
Continued relaxation due to inhibition of acetylcholine destruction
Continued contraction due to inhibition of acetylcholine activity
Continued relaxation due to inhibition of acetylcholine activity
25) The effect of nerve gas on cardiac muscle is: pg 83
A)
B)
C)
D)
Continued contraction due to inhibition of acetylcholine destruction
Continued relaxation due to inhibition of acetylcholine destruction X
Continued contraction due to inhibition of acetylcholine activity
Continued relaxation due to inhibition of acetylcholine activity
26) The open channel of the Acetylcholine Receptor is large enough to allow flow of either Na+
or K+ through it. The function of which of the following proteins on the postsynaptic
membrane at rest ensures that Na+, rather than K+, flows through the receptor when it is
stimulated to open by neurotransmitter: not covered
A)
B)
C)
D)
Voltage gated K+ channel
K+ leak channel X
Na+ leak channel
Voltage gated Na+ channel
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27) Which of the following protein-labeling techniques could be used in FRAP analyses to
measure how dynamic the protein is in a plasma membrane. pg 6, 71
A)
B)
C)
D)
Immunostaining of a fixed cell with fluorescently labeled antibody
In vitro labeling of the protein with Gold particles and injection of it into the living cell
Expression of a GFP-tagged version of the protein in the living cell X
All of the above
28) Which of the following is an example of an amphipathic molecule: pg 64, 67, 74
A)
B)
C)
D)
SDS
Cholesterol
Phosphoglyceride
All of the above X
29) Which of the following terms applies to a membrane protein that spans the entire width of
the lipid bilayer pg 71
A)
B)
C)
D)
Peripheral
Integral X
Lipid-anchored
Carbohydrate-anchored
30) Which of the following membrane proteins functions in passive transport across the
membrane: pg 80, 87, 86, 78, 79
A)
B)
C)
D)
Na+/K+ ATPase pump
CFTR ABC transporter
Voltage-gated K+ channel X
Bacteriorhodopsin
31) Which of the following describes a reaction in which the reactants contain higher bond
energies than the products and reactants that are more highly ordered than the products: pg
33
A) ∆H<0 and ∆S>0 X
B) ∆H>0 and ∆S<0
C) ∆H>>0 and ∆S=0
D) ∆H=0 and ∆S<<0
32) A reaction with which of the following thermodynamic parameters would NOT be expected
to occur without external energy: pg 33
A) ∆H<0 and ∆S>0
B) ∆H=0 and ∆S>>>>>0
C) ∆H<<<<0 and ∆S=0
D) ∆H=0 and ∆S<<0 X
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33) Which of the following reactions of the glycolytic
pathway shown to the left would be the least likely to occur
spontaneously under standard conditions:
pg 33
A) 2 X
B) 4
C) 6
D) 8
34) Which of the following reactions is required to drive the
reaction coming before it forward: pg 36, 46
A) 2
B) 4
C) 6
D) 8 X
35) Which of the following reactions is an example of a
REDOX reaction: pg 45
A) 2
B) 4 X
C) 6
D) 8
36) Which of the following reactions is an example of
substrate level phosphorylation: pg 44
A) 2
B) 4
C) 6
D) 8 X
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37) Use the Table of Standard Redox
Potentials shown to the right to
determine which of the following
electron transfer reactions will occur
spontaneously in the direction written
under standard conditions: pg 51
A)
B)
C)
D)
from ethanol to NAD+
from ethanol to Ubiquinone X
from H2O to NAD+
from Ubiquinol to Fumarate
38) Use the Table of Redox Potentials and
the Faraday constant (23.063 kcal/ V .
mol) to determine which of the
electron transfer reactions in question #14 above will release sufficient energy to allow
synthesis of 1 mol ATP under standard conditions: pg 51
A)
B)
C)
D)
from NADPH to NAD+
from ethanol to Ubiquinone X
from ethanol to pyruvate
from Ubiquinol to Oxaloacetate
ESSAY SHORT ANSWER
Give your answers to the following questions in your exam booklet only.
39) The epi-fluorescence microscope allows you to observe the cellular distribution of a specific
molecule, such as a protein, that has been appropriately labeled.
A) Describe how this works, including names of the specific components of the epifluorescence microscope not present in the traditional light microscopy that allow it to do
this. (4 pt) pg. 5
The epifluorescence microscope uses light of a single wavelength instead of the full light
spectrum. (+1) The light wavelength used excites the fluorescent label on the molecule of
interest. (+1) An excitation filter between the light source and the sample allows only that
wavelength of light to reach the sample. (+1) Then a barrier filter between the sample and the
eye allows only light of the wavelength that is emitted from the excited fluorescent label to reach
the eye. (+1)
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B) Describe two different methods for labeling a protein so that it can be visualized by epifluorescence microscopy. (4 pt) pg. 6
Any 2 of the following:
1) Covalently linking a fluorescent probe directly to the purified molecule in vitro.
2) Immunofluorescene-use an antibody that recognizes the molecule of interest that has a
fluorescent probe covalently linked to it.
GFP tagging of a protein-express a recombinant form of the gene encoding a protein of interest
that has been fused to the gene encoding Green Fluorescent Protein (GFP)
40) The electron microscope offers higher resolution than the light microscope.
A) Explain what is meant by the term “higher resolution”. (2 pt) pg. 2
Resolution is measured as the distance between 2 pts that can be discriminated from one another.
The distance is smaller with higher resolution. (2 pts)
(1pt credit given for answers saying that higher resolution means you can see more details in the
image.)
B) List two variables you could control to maximize the resolution of your light (or epifluorescence microscope. (2 pt) pg. 2
2 or more of the following:
Use the lowest wavelength of light in the spectrum. Use a lens with a high numerical aperture.
Use a mounting medium that reduces scatter of light diffracted from specimen. Have ocular and
objective lens closer together (to reduce light scatter). Etc.
Not accepted: focus the microscope, use a higher magnification lens, etc.
C) Explain why the electron microscope is able to offer higher resolution than the light
microscope. (2 pt) pg. 2, 4
The accelerated electrons in an electron beam has a lower wavelength than the shortest
wavelength of light in the spectrum. (2 pts)
10
41) You are doing a BIO 395 independent research project in a cancer research lab. You have
been assigned a project of using microscopy to study a new protein the lab recently purified
from a particular cancer cell type. Your advisor has several questions about the protein and
the cancer cell it comes from. You have a traditional light microscope, an epifluorescence microscope, and an electron microscope available for your studies, but since
your budget and energy level are limited you must choose the method that is most suited to
each question. (HINT: Each type of microscope will be used once and only once.) For
each question listed below (parts A, B, and C): 1) choose the type of microscope you will
use, 2) explain why it’s the best choice, and 3) describe any reagents you will need to make
before you can do the experiment:
A) At low resolution, what is the general size and shape of the cancer cells the protein was
purified from? (1pt ea)
1) Which type of microscope will you use to determine this?
Light microscope
2) Why is it most suited for answering this question?
Only low resolution required, no need to observe a specific molecule
3) What, if any, reagents will you need to make first?
None
B) You have found the cells to be flat and round. Your question now is: At relatively low
resolution, where is the protein located in the cell? (1pt ea)
1) Which type of microscope will you use to determine this?
Epifluorescence microscope
2) Why is it most suited for answering this question?
Only low resolution required, but there is a need to observe a specific molecule
3) What, if any, reagents will you need to make first?
Either a fluorescently-labeled antibody against the protein, a GFP fusion of the
protein, or an in vitro fluorescently labeled protein.
C) You have determined that the protein is located on the plasma membrane. Your question
now is: At higher resolution, where on the plasma membrane it is located? (1pt ea)
1) Which type of microscope will you use to determine this?
Electron microscope
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2) Why is it most suited for answering this question?
High resolution AND specificity required
3) What, if any, reagents will you first need to make?
Gold-labeled protein or antibody against protein
42) Briefly describe each event in stimulating an action potential on a skeletal muscle membrane
listed below. Start by defining the term action potential. Then include the 1) value of the
membrane potential at each step, 2) names of specific membrane protein or proteins involved
and 3) what each does: pg 81, 82
Define Action Potential: (1 pt)
Change in membrane potential (ion concentration gradient) to threshold in response to neural
stimulation
A) Establish resting membrane potential, with K+ at equilibrium (5 pt)
1) -70 mV (+1)
2) Na+/K+ ATPase (+1), with K+ leak channel (+1)
3) Na+/K+ ATPase sets up electrochemical gradient on resting membrane by moving 3 Na+ out
for every 2 K+ moved in. (+1) The K+ leak channel allows K+, but not Na+, to be at
equilibrium.(+1)
B) Depolarization to threshold (3 pt)
1) -50 mV (+1)
2) Neuroreceptor (+1)
3) Binding of neurotransmitter opens an ion channel that allows Na+ to flow in.
C) Full Depolarization (3 pt)
1) +50 mV (+1)
2) Voltage Gated Ca2+ Channel (+1) (0.5 pt for saying Voltage Gated Na+ Channel)
3) Voltage change with depolarization to threshold triggers Channel to open and let more cation
in.
D) Repolarization (3 pt)
1) -80 mV (+1)
2) Voltage Gated K+ Channel (+1)
3) Voltage change with full depolarization triggers Channel to open and let K+ out.
12
43) The same neurotransmitter can have a stimulatory effect on the postsynaptic membrane of
one cell type but an inhibitory effect on the postsynaptic membrane of a different cell type.
Describe two mechanisms that might allow different postsynaptic membranes to have
different responses to the same neurotransmitter. (2 pt) pg 83
Different neuroreceptors on the two postsynaptic membranes (that let different ions through)
Different ion leak channels on the two postsynaptic membranes (that let different ions be at
equilibrium)
44) Briefly (< 1 page) explain how proton translocation through the Fo base of ATP synthase
stimulates the ATP synthesizing activity of the F1 head. Include in your description: 1)
names and activities of all relevant subunits (6 pt), 2) location of the enzyme in the
mitochondria and direction of H+ transport relative to that location (2 pt), 3) ratio of H+
translocated to ATP molecules produced (2 pt). (10 pt. total) pg 58, 59
H+ from the intermembrane space of the mitochondria bind the Asp61 residue of each of 12 c
subunits in a c ring (+1) that is embedded in the inner membrane. (+1) . Binding of H+ to the c
subunit powers a conformational change that causes rotation of the c ring. (+1) After a 360o
rotation of the c ring, an H+ picked up from the IM space will be released into the matrix space.
The end result is translocation of H+ from the IM space to the matrix space (+1). The rotation of
the c ring, causes rotation of the attached γ subunit (+1) that projects into the matrix space and is
surrounded by 3 fixed catalytic β subunits. As the γ subunit rotates, it induces a series of
conformational changes in the β subunit (+1) from an Open (O), Loose (L), Tight (T)
conformation. (+1) The O conformation allows binding of substrates ADP and Pi, the L
conformation allows loose binding of the substrates, while tight binding allows them to be
covalently linked to form ATP. (+1) For each 360o rotation of the c ring, 12 H+ (+1) are
translocated from the IM to matrix space and each of the 3 β subunit is able to go through all
three conformations to make a total of 3 ATP(+1).
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