Question 1

How does EGTA block microtubule polymerization?

Accepted Answer

A) It binds Ca2+ ions,which inhibit microtubule polymerization. 
B) It binds Mg2+ ions,which inhibit microtubule polymerization. 
C) It binds Ca2+ ions,which stabilize microtubule polymerization. 
D) It destroys Ca2+ ions,which inhibit microtubule polymerization. 
E) It destroys Mg2+ ions,which inhibit microtubule polymerization.

Question 2

The focal complexes that form near the leading edge of a motile cell exert traction force through their associated __________ and then typically disassemble as the cell moves forward.

Accepted Answer

A) microtubules 
B) keratin filaments 
C) vinculin filaments 
D) actin filaments 
E) actinin filaments

Question 3

How are microtubules thought to affect cell shape in plants?

Accepted Answer

A) Microtubules of the plant cell cortex are thought to affect the movement of cellulose-synthesizing enzymes in the cell membrane,which,in turn,affect cell wall growth and shape. 
B) Microtubules of the plant cell vacuole are thought to affect the movement of cellulose-synthesizing enzymes in the cell membrane,which,in turn,affect cell wall growth and shape. 
C) Microtubules of the plant cell cortex are thought to affect the movement of lipid-synthesizing enzymes in the cell membrane,which,in turn,affect cell wall growth and shape. 
D) Microtubules of the plant cell wall are thought to affect the movement of cellulose-synthesizing enzymes in the cell membrane,which,in turn,affect cell wall growth and shape.

Question 4

When laser beams are shone through the objective lens of a microscope,a weak attractive force is generated near the point of focus.This allows the grasping of microscopic objects.Such a device is called a(n)______.

Accepted Answer

A) optical density 
B) optical tweezer 
C) confocal laser scanning 
D) absorbance microscopy 
E) laser pointer

Question 5

Of what protein are the arms attached to the A microtubule of the axoneme composed?

Accepted Answer

A) tubulin 
B) actin 
C) dynein 
D) keratin 
E) myosin

Question 6

________ proteins share considerable sequence homology with actins and accelerate the polymerization of actin filaments.

Accepted Answer

A) Actin-nucleating 
B) Actin-racemase 
C) Actin-related 
D) Tubulin-related 
E) Actin-rated

Question 7

Which technique below can be used to measure the mechanical properties of the cytoskeletal elements themselves?

Accepted Answer

A) laser beams 
B) atomic force microscopy 
C) transmission electron microscopy 
D) scanning electron microscopy 
E) SDS-PAGE

Question 8

Which of the following molecular motors is known to travel in a retrograde direction along microtubules?

Accepted Answer

A) kinesins 
B) dyneins 
C) myosins 
D) kinesins and myosins 
E) kinesins and dyneins

Question 9

The core of a cilium is called the ________.

Accepted Answer

A) troponeme 
B) dynomeme 
C) cilioneme 
D) axoneme 
E) flagelloneme

Question 10

Why would the addition of an irreversibly binding ATP analog to an in vitro system for monitoring molecular motors stop motor function?

Accepted Answer

The answer of Why would the addition of an irreversibly...

Question 11

What motor is associated with microfilaments?

Accepted Answer

A) myoglobin 
B) kinesin 
C) myosin 
D) dynein 
E) myometrium

Question 12

Which of the following would be an accurate title for a movie about the mechanism of muscle contraction?

Accepted Answer

A) Sliding Lamina 
B) Shortening Filaments 
C) Sliding Filaments 
D) And Then There Were Two 
E) Filaments At Large

Question 13

Which of the following nonmuscle cell activities do not involve actin filaments often working in concert with myosin motors?

Accepted Answer

A) cytokinesis 
B) blood platelet activation 
C) vesicle trafficking 
D) red blood cells carrying oxygen 
E) changes in cell shape

Question 14

A scientist observes the motion of a certain type of vesicle around the cell.She notices that vesicle movement ceases when colchicine is added to the culture medium.What conclusion can she draw?

Accepted Answer

The answer of A scientist observes the motion of a...

Question 15

What accounts for the decrease in the length of an entire muscle?

Accepted Answer

A) the combined decrease in sarcomere length 
B) the combined shortening of actin filaments 
C) the combined shortening myosin filaments 
D) the combined shortening of thin filaments 
E) the combined decrease in sarcomere length and the combined shortening of actin filaments

Question 16

One of the WASP/WAVE family of proteins,specifically WASP,the founding member of the family,is associated with what disease below?

Accepted Answer

A) hemophilia 
B) Wiskott-Aldrich syndrome 
C) lymphoma 
D) lupus erythematosus 
E) Wallace's syndrome

Question 17

An intermediate filament can stretch up to _____ its normal length before it breaks into two pieces.

Accepted Answer

A) 1.5 
B) 2.5 
C) 3.5 
D) 10 
E) 35

Question 18

What chemical below is known to free actin monomers and block their incorporation into the polymer?

Accepted Answer

A) cytochalasins 
B) nocodazole 
C) phalloidin 
D) latrunculin 
E) phalloidin and latrunculin

Question 19

What provides the energy that drives sarcomere contraction?

Accepted Answer

A) ATP 
B) ADP 
C) GTP 
D) GDP 
E) none of these choices

Question 20

Why is myosin V able to take very large steps along a microfilament?

Accepted Answer

A) Its neck is twisted. 
B) Its neck is relatively long. 
C) Its neck is relatively short. 
D) Its tail is very long. 
E) Its tail is bipolar.

Exam 9: The Cytoskeleton and Cell Motility