Bi0282b Midterm 2 Cell-cell adhesion complexes are associated with specific

26 Jun Bi0282b Midterm 2 Cell-cell adhesion complexes are associated with specific

Question
1. Cell-cell adhesion complexes are associated with specific cytoskeleton systems. Which of
these adhesive complexes are linked to intermediate filaments?
A) focal adhesions
B) adherence junctions
C) desmosomes
D) gap junctions
E) tight junctions
2. Separation of spindle poles during anaphase B utilizes which of the following?
A) (+) end-directed microtubule motors at the cell membrane
B) (+) end -directed microtUbule motors at the kinetochore
C) (-) end-directed microtubule motors on overlapping polar microtubules
D) (+) end-directed microtubule motors on overlapping polar microtubules
E) both A and C.

3. Which protein is expressed in a cell-specific manner and binds to the tripeptide sequence
Arg-Gly-Asp?
A) integrin
B) collagen
C) laminin
D) fibronectin
E) both C and D

.

4. During mitosis
A) all chromosomes must be captured.
B) the microtubule network becomes more stable.
C) treadmilling is not utilized.
D) the plasm(i membrane is degraded.
E) no energy is required.
5. If actin within a sarcomere is decorated with S 1 myosin the "arrow heads" will point to
A) the Z disk.
B) tropomodulin.
C) capZ.
D)AandC.
E) None of the above.
6. A migrating cell expressing a5~1 integrin stops migrating when it reaches a new substrate.
Migration stopped because
A) no more collagen substrate was available.
B) no more fibronectin substrate was available.
C) no more laminin substrate was available.
D) no more lamin substrate was available.
E) no more carbohydrate substrate was available . .

1

Bi0282b Midterm 2

CODE 111

Sunday March 9, 1 – 2:30pm.

7. Microtubules within a dendrite are composed of’ _ _ _ _ protofilaments.
A) 10
B)13
C) 23
D)33
E) two of the above

–

8. What two proteins are found at the indicated "New adhesion" spot on this migrating cell?

A) Cadherin and actin.
B) Integrin and actin.
C) Integrin and lamin.
D) Cadherin and vimentin.
E) Integrin and keratin.
9. A y-tubulin antibody is added into a plant cdl where it labels hundreds of individual spots
within that cell. This labelling pattern indicates that
A) plant tubulin dimers are composed ofa andy subunits.
B) plants have many basal bodies.
C) plants have hundreds of centrioles.
D) plants have many MTOCs.
E)plant cell walls are supported by microtubules.

10. During treadmilling, actin subunits add
A) predominantly to filament (+) ends.
B) predominantly to filament (-) ends.
C) equally to both filament ends.
D) along the entire length of a filament.
E) in the GTP form.
11. Microtubule assembly can occur
A) if microtubule-associated proteins are hydrolyzed.
B) if cells are incubated at 4°C.
‘
C) when A TP is hydrolyzed.
D) when CAMs are utilized.
E) when the tubulin subunit concentration is in excess ofthe Cc.

2

Bi0282b Midterm 2

CODE 111

Sunday March 9,1 – 2:30pm.

12. The sarcoplasmic reticulum must have membrane proteins that can
A) bind to tropomyosin and troponin.
B) depolymerize.
C) release and pump Ca2+.
D) contract.
E) promote cell adhesion.
13. Microtubules can be destabilized at the (+) end by _ _ _ _ and_ _ _ _, the latter of
which requires _~
A) stathmin, katanin, MTOC
B) stathmin, kinesin, A TP
C) stathmin, kinesin, MTOC
D) katanin, stathmin, GTP
E) katanin, kinesin, ATP
14. If actin has a Cc+ of O.121lM and a Cc- of O.6IlM, what would result if excess amounts of
CapZ were present and the concentration of free ATP bound G-actin is O.9IlM?
A) There would be growth at both the (+) and (-) ends.
B) There would be depolymerization at both the (+) and (-) ends.
C) There would be depolymerization only at the (-) end.
D) There would be growth at only the (-) end.
E) There would be growth at only the (+) end.
15. With respect to the graph below that depicts microtubule length with respect to time, what
event could have triggered a catastrophe?
A) Excess ‘Y-tubulin.
B) Depletion of GTP-tubulin.
C) Increasing temperature to 37°C . .’
D) Inadequate IF APs.
E) Excess dynein.

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3

Bi0282b Midterm 2

CODE 111

Sunday March 9, 1 – 2:30pm.

16. During mitosis in animal cells
A) nuclear membrane breakdown occurs after metaphase.
B) the centrioles replicate after metaphase.’
C) the nuclear DNA is replicated after metaphase.
D) anaphase occurs after metaphase.
E) All of the above.
I,

17. With respect to actin polymerization where there is ample G-Actin in the ATP form, the
presence of nuclei (short F -actin polymers) will
A) decrease the time needed to reach steady state.
B) increase the time needed to reach steady state.’ ‘
C) decrease the critical concentration of the plus end.
D) increase the critical concentration of the plus end.
E) inhibit polymerization.
18. Which of the following properties is not shared by all myosins?
A) The ability to bind ATP.
B) They move to the (+) end of actin.
C) The ability to form dimers.
D) The ability to bind actin.
E) The presence of a head domain.
19. Which of the following proteins is involved in the formation of actin bundles in microvilli?
A) a-actinin
B) cofilin>
C) fimbrin’
D) profiling
E) tau
20. Membrane extension during cell locomotion is driven by
A) myosin II.
B) focal adhesions.
C) sarcomeres.
D) actin polymerization.
E) adherens junctions.
21. All ofthe following are actin based structures, except
A) flagella
B) filopodia
C) microvilli
D) stress fibers
E) adherens junctions

4

Bi0282b Midterm 2

CODE 111

Sunday March 9, 1 – 2:30pm.

. 22. The force for axoneme bending is derived from the
A) sliding movement of the central singlet microtubules.
B) contraction of central singlet microtubules.
C) sliding movement of outer doublet microtubules.
D) contraction of outer doublet microtubules.
E) bi-polar motor driven microtubule movements.
23. A cell is treated with taxol and subsequent analysis revealed that it could not migrate, but that
it had its keratin filaments intact. From this description we can deduce that
A) the actin cytoskeleton was depolymerized.
B) the actin cytoskeleton was stabilized.
C) the cell’s myosin was inactive.
D) the cell was epithelial.
E) the cell was dead.
24. With respect to cell migration, which is the correct sequence of events?
A) Rac activation at the front of a cell allows Rho activation of Arp2/3 and subsequent
WASp activation and myosin activation.
B) Cdc42 activation at the front of a cell allows Rac activation of Arp2/3 and subsequent
Rho activation and myosin activation.
C) Cdc42 activation at the back of a cell allows Rac activation of Arp2/3 and subsequent
Rho activation and actin activation.
D) Cdc42 activation at the front of a cell allows WASp activation of Rho and subsequent
myosin activation.
E) Rac activation at the front of a cell allows WASp activation of ArP2/3 and subsequent
Rho activation and actin activation.
25. You are given a culture dish in which cells are adhering to each other. You then add EDTA
to the culture. EDTA binds to and removes all calcium from the culture solution. After the
EDTA treatment all of the cells remain bound to each other as they did before. From this
observation you can conclude that:
A) the cells are all expressing cadherin molecules.·
B) the cells are all expressing Ig superfamily CAMs.
C) half the cells are expressing N-Cad, while the other half are expressing
complementary N-CAM molecules on their surface.
D) the cells are adhering to each other using integrins.
E) the cells are adhering to each other using hemidesmosomes.
26. The plasma membrane of eukaryotic cells is supported by
A) actin filaments.
B) rnicrotubules.
C) larnins.
D) clathrin. ·
E) myosin II.

5

Bi0282b Midterm 2

CODE 111

Sunday March 9, 1 – 2:30pm.

27. Which of the following occurs during anaphase A?
A) The spindle elongates.
B) The aster elongates.
C) Kinetochores remain attached to shortening kinetochore microtubules.
D) Chromosomes move to the spindle equator.
E) The spindle poles move closer together.
28. Vertebrate gap junctions are composed of
A) adherins.
B) collagens.
C) cadherins.
D)integrins.
E) none of the above.
29. A mutation arises which renders kinesin-5 non-functional. As a result
A) trafficking of vesicles from the ER to the Golgi will cease.
B) anterograde trafficking of vesicles will cease.
:::
C) anaphase B will be interfered with.
D) cytokinesis will be interfered with.
E) Retrograde trafficking of vesicles will cease.
30. The kinetochore
A) is made of DNA.
B) contains two asters.
C) is an actin attachment site.
D) is associated with the centromere.
E) contains centrioles.

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