Deck 17: Cell Organization and Movement II: Microtubules and Intermediate Filaments

Question 1

A drug that prevents microtubules from depolymerizing could be used to:

A)stimulate cytokinesis.
B)inhibit mitosis.
C)promote cell division.
D)treat Alzheimer's disease.

Answer 1

B

Question 2

Which of the following is NOT a way in which a microtubule switches from growing to shortening?

A)loss of GTP cap
B)treatment with colchicine
C)binding of MAP2
D)binding of stathmin

Answer 2

B

Question 3

At MTOCs,microtubule nucleation is facilitated by:

A)centrioles.
B)γ-tubulin.
C)GDP-tubulin dimers.
D)basal bodies.

Answer 3

B

Question 4

The EB1 protein has several functions.Which of the following is/are true regarding EB1?

A)It promotes microtubule growth by enhancing polymerization at the (+)end.
B)Other microtubule plus-end tracking proteins use EB1 to "hitchhike" onto the growing microtubule.
C)It can bind further back from the blunt end of microtubules.
D)all of the above

Question 5

A microtubule protofilament is formed by the:

A)lateral association of only γ-tubulin subunits.
B)head-to-tail association of only γ-tubulin subunits.
C)lateral association of tubulin dimers.
D)head-to-tail association of tubulin dimers.

Question 6

What is a microtubule protofilament?

Question 7

Where are microtubules observed to be present in different polarities?

A)axons of nerve cells
B)animal cells in interphase
C)animal cells in mitosis
D)dendrites of nerve cells

Question 8

Growing microtubule ends are normally stabilized by:

A)a GDP cap.
B)a GTP cap.
C)phosphorylation of tubulin subunits.
D)γ-tubulin.

Question 9

The region of a motor protein that interacts with the motor's cellular cargo is the:

A)head domain.
B)tail domain.
C)rod domain.
D)light chains.

Question 10

The _____ serves as a template for the unusual structure of axoneme microtubules.

A)γ-tubulin ring complex
B)pericentriolar material
C)centrosome
D)basal body

Question 11

All of the following statements describe kinesin-I EXCEPT:

A)kinesin-I is a (−)end-directed motor.
B)kinesin-I transports vesicles along microtubules.
C)kinesin-I binds and hydrolyzes ATP to produce movement.
D)kinesin-I is composed of two heavy chains and two light chains.

Question 12

Microtubule assembly requires:

A)microtubule-associated proteins.
B)incubation at 4°C.
C)ATP.
D)a tubulin concentration in excess of the Cc.

Question 13

In most cells,where do all microtubules originate?

Question 14

In cells,the γ-tubulin ring complex is found:

A)in the hollow core of the microtubule.
B)at the microtubule (−)end.
C)at the microtubule (+)end.
D)along the outer wall of the microtubule.

Question 15

The alpha and beta tubulin proteins can bind:

A)to ATP or ADP.
B)to GTP or GDP.
C)only to GDP.
D)none of the above

Question 16

What happens to a microtubule that loses its GTP cap?

Question 17

What are the effects of colchicine and taxol on cells?

Question 18

MAP2 and Tau are examples of microtubule:

A)destabilizing proteins.
B)motor proteins.
C)nucleating proteins.
D)stabilizing proteins.

Question 19

The drug taxol acts to:

A)block microtubule assembly.
B)stabilize microtubules against depolymerization.
C)promote cell division.
D)sever microtubules.

Question 20

For kinesin motors,the direction of movement along a microtubule is specified by the motor's:

A)motor (head)domain.
B)neck region.
C)stalk domain.
D)tail domain.

Question 21

Which of the following is NOT true about cilia?

A)All cilia arise from nine sets of outer triplet microtubules (similar to centrioles).
B)Cilia contain the same transport system as flagella,called IFT.
C)All cells with cilia are motile because of the axonemal dynein motor.
D)Primary cilia contain receptors that increase the cell's responsiveness to its environment.

Question 22

Why would neuronal vesicles probably contain both kinesin and cytosolic dynein?

Question 23

Poleward movement of chromosomes during anaphase A requires:

A)microtubule polymerization.
B)ATP.
C)kinetochore motor proteins.
D)BimC.

Question 24

During late anaphase and telophase,the microfilament-based contractile ring facilitates pinching the cell into two,but the ring must first be positioned equidistant between the two spindle poles before this occurs.Describe the mechanism whereby signals from the spindle direct the positioning of the contractile ring.

Question 25

Capture of microtubule (+)ends by chromosomes occurs during:

A)metaphase.
B)prometaphase.
C)anaphase.
D)telophase.

Question 26

The force for axoneme bending is derived from the:

A)sliding movement of central pair microtubules.
B)contraction of central pair microtubules.
C)sliding movement of outer doublet microtubules.
D)contraction of outer doublet microtubules.

Question 27

Which of the following is true regarding the transport of cargo by cytoplasmic dynein?

A)Dynactin is the protein that links dynein to microtubules.
B)Transport is toward the (+)end of the microtubules.
C)GTP binds to the head region of dynein.
D)LIS1 associates with the head region of dynein to facilitate transport.

Question 28

What function do kinetochore-bound motor proteins perform during anaphase A?

Question 29

What is the role of the basal body in generating axoneme structure?

Question 30

What motor protein generates the force to cause axoneme bending?

Question 31

Separation of spindle poles during spindle formation and anaphase B most likely depends on which of the following?

A)(+)end-directed microtubule motors at the cell cortex
B)(+)end-directed microtubule motors at the kinetochore
C)(−)end-directed microtubule motors in the microtubule overlap zone
D)(+)end-directed microtubule motors in the microtubule overlap zone

Question 32

During mitosis,the breakdown of the nuclear envelope depends on the disassembly of lamin filaments that form a meshwork supporting the membrane.How is that breakdown accomplished?

Question 33

Kinetochores assemble at the:

A)centrosome.
B)spindle pole.
C)telomere.
D)centromere.

Question 34

The primary cilium:

A)is nonmotile because it lacks the "central pair" of microtubules.
B)is relatively susceptible to microtubule destabilizing drugs like colchicine.
C)has no known role in humans.
D)none of the above

Question 35

Which of the following does NOT belong to the intermediate filament protein family?

A)vimentin
B)keratin
C)laminin
D)desmin

Question 36

Treadmilling through kinetochore microtubules can be observed by:

A)simple fluorescence microscopy.
B)optical trap microscopy.
C)fluorescence speckle microscopy.
D)electron microscopy.

Question 37

In the mitotic spindle,astral microtubules function to:

A)connect the spindle poles.
B)attach chromosomes to the spindle.
C)carry out cytokinesis.
D)anchor the spindle poles to the plasma membrane.

Question 38

What role do astral microtubules play in spindle elongation?

Question 39

What effect will addition of AMP-PNP have on axonal transport?

Question 40

Which of the following occurs during anaphase A?

A)The spindle elongates.
B)Kinetochores remain attached to shortening kinetochore microtubules.
C)Chromosomes move to the spindle equator.
D)The spindle poles move closer together.

Question 41

Which of the following is true about intermediate filaments?

A)They are named based on their location in cells between actin microfilaments and microtubules.
B)All cells express the same class II cytoplasmic intermediate filament proteins.
C)Staggered,antiparallel tetramers give intermediate filaments strength.
D)Acidic and basic keratins provide dynamic paths on which organelles may travel.

Question 42

In studies of wound healing,it was noticed that when the cells at the edge are induced to polarize and move to fill the wound,the Golgi complex moves to the front of the nucleus toward the cell front.What is the purpose of this reorientation and how is it accomplished?

Question 43

The important role that intermediate filaments play in the epithelial cells of the skin is evident in which of the following?

A)Individual keratin filaments span the cell membrane and directly connect one cell to the next.
B)Knockout mice for a keratin gene like K14 exhibit stronger skin that can withstand abrasion.
C)The polarity of keratin filaments allows them to withstand shear stress.
D)Patients with mutations in keratin genes exhibit skin problems.