Name______________________
Section____
Exam 2
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content of this exam in any form, nor have I received such information from
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Date
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Multiple choice _____/40
Short Answer
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Long answer
_____/10
Total
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Name______________________
Section: 12:30 / 2:00
Exam 2
Multiple choice and T/F (2 points each): Choose the best possible answer for each.
1. What type of vesicle would you expect a protein with an ER exit signal to be inside of?
a. Clathrin
b. CopI
c. CopII
d. None of the above
2. If the centrosome is near the ER, what type of motor would you expect to be carrying a
COPI coated vesicle?
a. Kinesin
b. Dynein
c. Myosin
d. Not enough information to answer
3. What type of molecules are PIPs?
a. Proteins
b. Nucleotides
c. Phospholipids
d. None of the above
4. During PCR (polymerase chain reaction) what is the purpose of raising the sample to
98C?
a. Open up the template DNA
b. To allow the primers to anneal to the template DNA
c. To encourage the DNA polymerase to copy the template DNA
d. To make sweet sweet 90s pop music
5. Which of the following would you expect to find primarily inside the nucleus.
a. Ran-GAP
b. Ran-GEF
c. Ran-GDP
d. All of the above
6. Which of the following produce their own food?
a. Algae
b. Protozoa
c. Yeast
d. Both a and c
7. Kinesin-13 is to microtubules as __________ is to actin
a. Myosin
b. Profilin
c. Thymosin
d. Formin
e. None of the above
8. Which of the following can help integrate proteins into the inner mitochondrial
membrane?
a. TIM23
b. TIM22
c. OXA complex
d. All of the above
9. Which region of the graph below corresponds to actin shrinking at both the plus and
minus ends?
A
B
C
a.
b.
c.
d.
e.
A
B
C
None of the above
Both A and B
0
10. Which protein does the bacteria listeria monocytogenes recruit to form the actin comet
tail that propels the bacteria through its eukaryotic host?
a. Profilin
b. Formin
c. Gamma tubulin
d. Arp2/3
11. Which of the following prokaryotes is most likely the closest relative of Eukaryotes?
a. Lokiarchaota
b. Methanogenic archaea
c. Cyanobacteria
d. Yeast
12. T/F Myosin heads bound to ATP bind tightly to actin filaments.
13. Select the option that correctly lists the rings of the nuclear pore complex correctly from
inside to outside.
a. Membrane ring proteins, scaffold nucleoporins, channel nucleoporins
b. Channel nucleoporins, scaffold nucleoporins, membrane ring proteins
c. Membrane ring proteins, channel nucleoporins, scaffold nucleoporins
d. Channel nucleoporins, membrane ring proteins, scaffold nucleoporins
14. Which amino acid receives a poly-ubiquitin tag before a protein gets sent to the
proteasome?
a. Serine
b. Threonine
c. Lysine
d. Cystine
15. T/F Proteins with a nuclear import sequence will never be found outside the nucleus.
16. Which of the following resident ER proteins contain a stop transfer sequence?
a. SRP receptor
b. ER-protein translocator
c. Calnexin
d. All of the above
e. Both a and b
17. During cellular fractionation, from what spin would you collect the pellet if you wanted
to purify the TOM protein from your sample?
a. Low speed
b. Medium speed
c. High speed
d. Very high speed
18. Which portion of the microtubule dimer binds to GTP?
a. alpha
b. beta
c. gamma
d. theta
19. T/F SUN domain proteins directly bind to nuclear lamina.
20. Why did the researchers in Paper 1 replace the Dictostelium stalkhead with a stalkhead
derived from humans?
a. They thought it would be more relevant to diseases
b. The human stalkhead increased the dynein’s affinity for microtubules
c. The human stalkhead decreased the dynein’s affinity for microtubules
d. It made the dynein remain in monomers instead of dimers
Short answer and matching:
21. Based on what you know about how the cytoskeleton is organized in cells, why do you
think microtubules have plus and minus end motors while actin has (mostly) only plus
end motors? (4 points)
Microtubules are typically all oriented in parallel, so all plus ends are on the same side. This
means you need minus end motor proteins to move things toward the MTOC. Actin can be
organized anti parallel so the plus end of actin filaments are found all over in the cell and
therefore most places can be reached by + end motors.
22. For each of the following, indicate which type of nucleotide it is associated with. (6
points)
Tubulin dimers
Dynamin
Actin monomers
Sar1
Myosin
Ran
__GTP__
__GTP__
__ATP__
__GTP__
__ATP__
__GTP__
23. Sort the following proteins based on where they would be synthesized. (7 points)
v-snare, lamin, Clathrin, TOC, Rab-5, KDEL receptor, SRP(the protein portion)
ER
v-snare
KDEL receptor
Cytosol
SRP
lamin
Clathrin
TOC
Rab-5
24. Explain step by step how a protein gets into the thylakoid lumen. Include any proteins
involved in allowing the protein to pass through membranes. Choose only one method
of thylakoid entry. (4 points)
Answer must include TIC, TOC and one of the following (sec pathway, srp, tat, or spontaneous
insertion) for full credit
25. Why is gene duplication important for evolution? (3 points)
One original copy of the gene will remain so that the original function is preserved. This allows
the second copy of the gene to mutate without killing the organism, even if the mutation would
normally be lethal.
26. Fill in the blanks. (abbreviations acceptable, 3 points)
___MLCK___ phosphorylates ___myosin light chain_ which causes the coiled coil tail of
__myosin heavy chain___ to straighten out and self-assemble with other myosin
proteins.
27. Starting with a newly translated protein, list 4 proteins discussed in class that the new
protein would contact on the way to the mitochondrial matrix. (4 points)
1. _cytoplamic hsp70_ 2. _TOM__ 3. ___TIM-23___ 4. __mito hsp70__
28. Explain the evolutionary relationship between eukaryotes, bacteria, and archaea. (4
points)
Eukaryotes are a merger of bacteria and archaea, all of which evolved from a common
ancestor.
I also gave credit if you described the venn-diagram we went over in class
29. Fill in the blanks below with the letter corresponding to the actin structure most
associated with each term listed. (4 points)
C
B
D
A
30. In the picture below indicate where you would find GTP vs GDP microtubule dimers in
the growing microtubule. (2 points)
GTP
Explain the behavior of the shrinking microtubule in
terms of protein conformation. Be specific. (4 points)
When microtubule dimers are bound to gtp they come
together in a curved conformation instead of straight.
This leads to catastrophe.
GDP
31. At the end of the discussion portion of the paper Imai, et al. make the following
statement “Dynein flexibility also raises new questions about the nature of the allosteric
communication between the ATPase cycle in the head and the MT binding affinity of the
stalkhead that is vital to dynein’s many cellular functions.” Explain in your own words
why this question is raised by the author’s findings. Use the figure below for reference
as needed. (5 points)
The authors show that the linkage between these two domains of the protein is not
rigid. This makes it hard to understand how changes in one part of the protein influence
the other part
If there is so much flexibility in the portion of the protein that links the motor domain to
the stalkhead, how do changes in the motor domain get translated to changes in the
stalkhead?
Long answer
32. Pick one protein we discussed in unit 2. Starting from the mRNA leaving the nucleus
explain (1) the processes required to get that protein to its final location and (2) how
the structure of the protein affects its function and localization.
Various answers
Extra credit: Do you think it would be possible to put an actin filament inside a microtubule.
Why or why not? (There’s not necessarily a correct answer here, but your reasoning must be
sound)