Download D-Glucose is a carbohydrate which can be classified as which of the

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Final Exam
Bio200: Cellular Biology
Winter 2013
Multiple Choice Questions
Circle the one best answer for each of the following questions. (2 points each)
1. Which one of the following is NOT considered to be a second messenger?
A. DAG
B. cAMP
C. PIP2
D. IP3
E. Ca2+
2. Which structure increases the rate with which an action potential can move down an axon?
A. Voltage-gated K+ channel
B. Basal lamina
C. Myelin sheath
D. Na+/K+ ATPase
E. None of these
3. Rosette complexes synthesize
A. tight junctions.
B. cellulose microfibrils.
C. microtubules.
D. collagen fibers.
E. the mitotic spindle.
4. Which structure includes a 9+2 arrangement of a key cytoskeletal fiber?
A. Centrosome
B. Contractile ring
C. Cilia
D. Kinetochore
E. Sarcomere
5. Preproinsulin is converted to proinsulin
A. in the target cell, either a hepatocyte or an adipocyte.
B. extracellularly.
C. during splicing.
D. in the Golgi of  -cells.
E. during its breakdown to shut off the signal.
6. When caspases have been activated in a mammalian cell, that cell
A. has been stimulated with glucagon.
B. has begun apoptosis.
C. enters G0.
D. initiates muscle contraction.
E. begins anaphase.
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7. The presence of a kinase cascade in a signal transduction pathway allows for
A. signal amplification.
B. long-term potentiation.
C. negative feedback.
D. crosstalk.
E. paracrine signaling.
8. Which statement correctly describes a GNEF?
A. This protein causes a Gprotein to exchange a GDP for a GTP.
B. This protein causes Ras to exchange a GDP for a GTP.
C. This protein causes a Gprotein to hydrolyze a GTP to a GDP.
D. This protein causes Ras to hydrolyze a GTP to a GDP.
E. None of the above
9. Which one of the following is an MTOC?
A. Sarcomere
B. Astral microtubule
C. Centromere
D. Basal body
E. Desmosome
10. The Origin Recognition Complex (ORC) is bound to the origin of replication throughout the cell
cycle, but can only function after the action of what protein?
A. APC
B. Cyclin/CDK
C. Myosin V
D. EGF-R
E. Caspase
11. An orphan receptor is a nuclear receptor which
A. binds to many different hormones.
B. has no known ligand.
C. is part of a different protein family.
D. is always found in the cytosol.
E. is always found in the nucleus.
12. Which kinase phosphorylates Lamin proteins, leading to their depolymerization?
A. Cyclin/CDK
B. Raf
C. PKA
D. APC
E. PFK
13. Which cell junction allows second messengers to move between adjacent cells?
A. Gap junctions
B. Adherens junctions
C. Tight junctions
D. Hemi-desmosomes
E. None of these
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14. Passing the Restriction Point requires
A. clathrin assembly.
B. caspase activation.
C. raising the membrane potential.
D. transcription of cyclin genes.
E. dynein activity.
15. Yeast encode two isozymes of hexokinase. Hxk1 has a Km 10-5M of and a Vmax of 2,500mmol/sec.
Hxk2 has a Km 10-3M of and a Vmax of 500mmol/sec. Which statement is true about these two enzymes?
A. The affinity of Hxk1 for the substrates is higher than Hxk2.
B. At high substrate concentrations, Hxk2 is more active than Hxk1.
C. Both enzymes are encoded by the same hexokinase gene.
D. At the same substrate concentration, both isozymes will have the same vi.
E. We expect both enzymes to have the identical secondary and tertiary structure.
16. The side chain of the amino acid Alanine is –CH3. The side chain of the amino acid Glutamate is –
CH2CH2-COOH, which has a pKa of 3. Draw the structure of N-Glutamate-Alanine-C, including any
charges that would be found at pH 7. (4 points)
17. What is the sequence of the anticodon of the one tRNA that is capable of translating all three
isoleucine (ile) codons? (2 points)
Wobble Rules
Anticodon Base
Codon Base
C
G
A
U
U
A or G
G
C or U
I
U, C or A
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18A. The gene encoding Glycogen Phosphorylase is present in essentially every cell in the human body.
Why is the Glycogen Phosphorylase protein only found in hepatocytes? (4 points)
18B. Your skeptical friend doubts the basis of the statement in 18A. Starting with samples of
eight different human tissues, what technique could you use to convince your friend that the
Glycogen Phosphorylase gene is present in all of these cell types? (2 points)
___________________________
18C. What technique could you use to convince your friend that the Glycogen Phosphorylase
protein is present only in hepatocytes? (2 points)
___________________________
19. Cadherin proteins are expressed in most human epithelial cells. The amino-terminus is on the outside
of the cell and the protein contains one transmembrane domain. On the diagram below, show the
targeting signals that are needed for the correct localization of Cadherin. (3 points)
N–
–C
19B. Name one type of junction where Cadherins will be found. _______________________
(2 points)
20. Name the one metabolic pathway described by each statement. (2 points each)
This catabolic pathway requires the enzyme Citrate
Synthase.
Human cells can use this pathway to synthesize
glucose from pyruvate or lactate.
This anabolic pathway uses CO2 as a substrate.
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21. Squid giant neurons have been a great model to help understand neuron transmission. We can isolate
a neuron and study it on a dish, surrounded by fluid that contains 150 mM Na+ and 5 mM K+. Under
normal conditions, if we stimulate a dendrite on these neurons, the axon releases the neurotransmitter
NAAG (N-acetylaspartyl glutamate). We can repeat this stimulation every few seconds and successfully
get NAAG release each time. (3 points each)
21A. If we change the extracellular fluid so that it contains 5 mM Na+ and 150 mM K+, the neuron
fails to release NAAG when stimulated. Please briefly explain why the neurotransmitter isn’t
released.
21B. We return the extracellular fluid to its normal conditions (150 mM Na+ and 5 mM K+) and treat
the neurons with the drug TTX, isolated from pufferfish. This drug physically blocks Na+ ions
from moving through the middle of the voltage-gated Na+ channel. Will this neuron release
NAAG each time that it is stimulated? Please briefly explain your answer.
21C. In the absence of TTX (and with normal conditions of the extracellular fluid), we add the drug
RTD32. This drug prevents the closing of the timing-dependent gate of the voltage-gated Na+
channel, but does not interfere with the voltage-dependent gate or the channel of this protein. Will
this neuron release NAAG each time that it is stimulated? Please briefly explain your answer.
21D. To determine if NAAG is an excitatory or inhibitory neurotransmitter, we need to look at the
post-synaptic cell. If NAAG is an inhibitory neurotransmitter, what protein do we expect to find
on the plasma membrane of the post-synaptic cell?
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22. Name the molecule, ion or cell structure that is described in each of the following statements about
muscle contraction. (2 points each)
This protein prevents proteins in the thick filament from
interacting with proteins in the thin filament.
This is a key second messenger that is released when the
muscle cell is stimulated to contract.
The second messenger is stored in this cell structure when the
muscle cell is relaxed.
The second messenger binds directly to this protein during
muscle contraction.
This structure gets shorter during muscle contraction.
This enzyme is found in the synapse of the neuromuscular
junction and helps to shut off muscle contraction.
23. Indicate whether each of the following statements describes intermediate filaments (IF),
microfilaments (MF), microtubules (MT) or none of these by circling your choices. Circle all that apply.
(1 point each)
Keratin is this type of structure.
This structure is essential for flagella movement.
The thick filament of skeletal muscles is this type of structure.
IF
IF
IF
MF
MF
MF
MT
MT
MT
none
none
none
This structure has two distinctly different ends.
This structure has a hollow interior.
IF
IF
MF
MF
MT
MT
none
none
Nuclear lamins are an example of this structure.
This structure is protected by a GTP cap.
This structure can interact with dyneins and kinesins.
IF
IF
IF
MF
MF
MF
MT
MT
MT
none
none
none
24. Name the molecule that is found in either a plant cell wall or the animal ECM which is described
below: (2 points each)
This molecule covalently cross-links microfibrils.
This transmembrane heterodimer indirectly connects collagen
fibers with the cytoskeleton
This molecule is made up only of an unbranched polymer of
monosaccharides connected in  14 linkages.
The fact that this enzyme is located extracellularly prevents
collagen from polymerizing prematurely.
This highly branched polysaccharide helps to resist
compression.
This proteoglycan helps to resist compression.
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25. We set out to study the signal transduction pathway of the plant hormone gibberellin. From the
published literature, we know that when certain plant cells are treated with gibberellin, the protein AP1
moves from the cytosol to the nucleus. We carry out the following experiments to learn more about this
pathway.
Treatment
AP1 localization
No hormone
Cytosol
none
+ Gibberrelin
Nucleus
No hormone
Cytosol
Caffeine (inhibits Phosphodiesterase)
+ Gibberrelin
Nucleus
No
hormone
Nucleus
Cholera Toxin (prevents G proteins
from cutting GTP to GDP)
+ Gibberrelin
Nucleus
No hormone
Cytosol
FTI (inhibits Ras function)
+ Gibberrelin
Nucleus
No hormone
Cytosol
U73122 (inhibits Phospholipase C)
+ Gibberrelin
Cytosol
No hormone
Cytosol
Cholera toxin and U73122
+ Gibberrelin
Cytosol
25A. What technique could we use in our studies to determine if the AP1 protein is in the nucleus or
the cytosol? (2 points)
25B. Based on this information, what can we deduce about this signal transduction pathway? (6 points)
26. Glucagon is an endocrine, peptide hormone that is produced by the  cells in the islets of Langerhans.
In the space below, describe the negative feedback regulation that shuts off the production of glucagon.
(4 points)
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27. Influenza virus enters human epithelial cells by receptor mediated endocytosis (similar to the uptake
of cholesterol in LDL particles. The key receptor protein is a glycoprotein, containing a sialic acid. Six
of the following nine statements happen during this process. List the six events in order below. (6 points)
A
B
C
D
E
F
G
H
I
A vSNARE on the vesicle interacts with a tSNARE on the endosome.
Clathrin is removed from the surface of the vesicle.
Dynamic instability increases.
Dynamin pinches off a clathrin-coated vesicle.
Glycoprotein receptors cluster in a clathrin-coated pit.
Glycoprotein receptors cross-phosphorylate.
The glycoprotein receptor is degraded.
The glycoprotein receptor is returned to the cell surface.
The lowered pH causes the virus to release the glycoprotein receptor.
First
Last
28. Each of the following five proteins (or protein complexes) plays a role in M phase. Choose any four
of the five and briefly explain their crucial role in M phase progression. (2 points each)

 Tubulin

APC

Cohesin

Myosin V

Ubiquitin
We’re done! Thanks for a good term and enjoy your break.
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