Question 1

The two main types of eukaryotic microtubules are the ________ and ________ microtubules.

Accepted Answer

cytoplasmi...

Question 2

Which of the following is not a function of the cytoskeleton?

Accepted Answer

A)  cell locomotion
B)  cell division
C)  organelle movement
D)  establishing cell shape
E)  passive transport

Question 3

The ________ is a complex network of interconnected filaments and tubules that extends throughout the cytosol from the nucleus to the inner surface of the plasma membrane.

Accepted Answer

A)  cytoskeleton
B)  microtubule apparatus
C)  axoneme
D)  desmin sheath
E)  microfilament array

Question 4

Intermediate filaments

Accepted Answer

A)  are 7 nm in diameter.
B)  can be composed of the protein vimentin.
C)  are abundant in plant cells.
D)  are the only cytoskeletal filament responsible for animal cell shape.
E)  A,B,C,and D.

Question 5

Which of the following cytoskeletal proteins would be expected to be involved in binary fission of a bacterium into two bacteria?

Accepted Answer

A)  FtsZ
B)  MreB
C)  plectin
D)  crescentin
E)  tubulin

Question 6

Activation of the ________ G-protein results in the extension of lamellipodia.

Accepted Answer

The answer of Activation of the ________ G-protein results in...

Question 7

Profilin does all of the following except

Accepted Answer

A)  competes with thymosin β4 for binding to actin monomers.
B)  sequesters actin monomers to prevent any polymerization.
C)  binds to formin in order to "stage" actin monomers for addition to a growing filament.
D)  promotes actin monomer addition to a filament plus end.
E)  Profilin does all of the above.

Question 8

Which technique would best be used to visualize movement of unlabeled vesicles along microtubules?

Accepted Answer

A)  immunofluorescence microscopy of fixed material
B)  live cell fluorescence microscopy
C)  computer-enhanced digital video microscopy
D)  deep-etch electron microscopy
E)  A,B,C,or D would be equally useful.

Question 9

The critical concentration for tubulin polymerization is the concentration of

Accepted Answer

A)  tubulin dimers at which all dimers assemble into microtubules.
B)  unassembled tubulin dimers when assembly is balanced with disassembly.
C)  tubulin dimers at which dimers assemble onto microtubule minus ends but disassemble from plus ends.
D)  unassembled tubulin dimers when there is net disassembly of dimers from both microtubule ends.
E)  tubulin dimers in most cells.

Question 10

Which of the following is false about lamellipodia?

Accepted Answer

A)  Their formation is stimulated by activation of Rac.
B)  They may have associated filopodia.
C)  They contain bundles of microtubules that push the plasma membrane forward.
D)  They extend at the leading edge of crawling cells.
E)  They contain branched networks of actin filaments.

Question 11

Which of the following proteins would be a good drug target for interfering with microfilament network breakdown?

Accepted Answer

A)  profilin
B)  CapZ
C)  gelsolin
D)  tropomodulin
E)  calmodulin

Question 12

What is the importance of proteins that precisely control when and where cytoskeletal elements polymerize and depolymerize? Make sure to give examples in your explanations.

Accepted Answer

Their precise control of filament existe...

Question 13

Microtubules and microfilaments are similar with respect to each of the following except

Accepted Answer

A)  inherent polarity of the structure.
B)  localization similar to that of intermediate filaments in cells.
C)  association with motor proteins.
D)  plus and minus ends for polymerization.
E)  both are polymers of subunits.

Question 14

Which phase of microtubule polymerization in vitro would be affected most by adding short microtubules to unpolymerized GTP-tubulin?

Accepted Answer

A)  lag phase
B)  elongation phase
C)  addition of tubulin dimers to microtubule (+) ends at the plateau phase
D)  addition of tubulin dimers to microtubule (−) ends at the plateau phase
E)  treadmilling

Question 15

Tubulin may assemble onto one end while disassembling from the other end of the same microtubule simultaneously in a process known as

Accepted Answer

A)  dynamic instability.
B)  treadmilling.
C)  nucleation.
D)  oligomerization.
E)  catastrophe-rescue.

Question 16

Describe an additional experimental approach used to study the cytoskeleton in which the activity of cytoskeletal elements is affected in ways similar to those resulting from drug treatment.

Accepted Answer

Using organisms or cell lines ...

Question 17

________ proteins promote depolymerization of existing microtubules at the ends.

Accepted Answer

The answer of ________ proteins promote depolymerization of existing microtubules...

Question 18

What is the effect of cofilin on an actin microfilament?

Accepted Answer

A)  caps the microfilament plus end
B)  caps the microfilament minus end
C)  increases turnover of ATP-actin at the microfilament plus end
D)  increases turnover of ADP-actin at the microfilament plus end
E)  increases turnover of ADP-actin at the microfilament minus end

Question 19

Activation of which of the following is associated with the formation of focal adhesions and stress fibers?

Accepted Answer

A)  Cdc42
B)  plectin
C)  Rho
D)  Rac
E)  γ-tubulin

Question 20

Based on composition similarities,actin can be divided into two major groups: the muscle-specific actins (________-actin)and nonmuscle actins (________- and ________-actin).

Accepted Answer

The answer of Based on composition similarities,actin can be divided...

Exam 13: Cytoskeletal Systems

Which technique would best be used to visualize movement of unlabeled vesicles along microtubules?

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Which of the following proteins would be a good drug target for interfering with microfilament network breakdown?

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Which of the following is not a function of the cytoskeleton?

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What is the effect of cofilin on an actin microfilament?

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Describe an additional experimental approach used to study the cytoskeleton in which the activity of cytoskeletal elements is affected in ways similar to those resulting from drug treatment.

Correct AnswerverifiedUsing organisms or cell lines ...View AnswerShow Answer

Based on composition similarities,actin can be divided into two major groups: the muscle-specific actins (________-actin)and nonmuscle actins (________- and ________-actin).

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Which phase of microtubule polymerization in vitro would be affected most by adding short microtubules to unpolymerized GTP-tubulin?

Correct AnswerverifiedShow Answer

Microtubules and microfilaments are similar with respect to each of the following except

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The ________ is a complex network of interconnected filaments and tubules that extends throughout the cytosol from the nucleus to the inner surface of the plasma membrane.

Correct AnswerverifiedShow Answer

Activation of which of the following is associated with the formation of focal adhesions and stress fibers?

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Intermediate filaments

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Tubulin may assemble onto one end while disassembling from the other end of the same microtubule simultaneously in a process known as

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Profilin does all of the following except

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The two main types of eukaryotic microtubules are the ________ and ________ microtubules.

Correct Answerverifiedcytoplasmi...View AnswerShow Answer

Which of the following is false about lamellipodia?

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Activation of the ________ G-protein results in the extension of lamellipodia.

Correct AnswerverifiedShow Answer

Which of the following cytoskeletal proteins would be expected to be involved in binary fission of a bacterium into two bacteria?

Correct AnswerverifiedShow Answer

What is the importance of proteins that precisely control when and where cytoskeletal elements polymerize and depolymerize? Make sure to give examples in your explanations.

Correct AnswerverifiedTheir precise control of filament existe...View AnswerShow Answer

________ proteins promote depolymerization of existing microtubules at the ends.

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The critical concentration for tubulin polymerization is the concentration of

Correct AnswerverifiedShow Answer

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Using organisms or cell lines ...
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Based on composition similarities,actin can be divided into two major groups: the muscle-specific actins (-actin)and nonmuscle actins (- and -actin).

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The two main types of eukaryotic microtubules are the and microtubules.

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cytoplasmi...
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Their precise control of filament existe...
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