Cell Bio Final Exam: Multiple Choice

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What word or phrase below characterizes the three cytoskeletal filaments?
a. polymer of protein subunits
b. protein subunits connected to one another by covalent bonds
c. protein subunits connected to one another by weak, noncovalent bonds
d. a and c
e. a and b

d

2. The advantage of the type of structure displayed by cytoskeletal filaments is that _________.
a. it lends itself to rapid assembly and disassembly
b. it is dependent upon and responsive to complex cellular regulation
c. it is tremendously stable
d. a and c
e. a and b

e

3. Which type of cytoskeletal element is characterized as a hollow, rigid cylindrical tube with walls composed of tubulin subunits?
a. microfilaments
b. microtubules (because microfilaments are helical)
c. intermediate filaments
d. all of the above
e. minitubules

b

Which type of cytoskeletal element is described as a solid structure composed of actin subunits?
a. microfilaments
b. microtubules
c. intermediate filaments
d. all of the above
e. macrofilaments

a

Which type of cytoskeletal element is described as a tough, ropelike fibers composed of a variety of related proteins like keratin?
a. microfilaments
b. microtubules
c. intermediate filaments
d. a and c
e. macrofilaments

c

Which of the following activities are identified as functions of the cytoskeleton?
a. a dynamic scaffold that provides structural support that helps to determine cell shape
b. internal framework that positions organelles in cell interior
c. a network of tracks that direct the movement of materials and organelles within the cell
d. a force-generating apparatus
e. all of the above

e

What kinds of materials appear to be moved around the cell by the tracks of the cytoskeleton?
a. mRNA molecules
b. membranous carriers between the ER and Golgi complex
c. transport vesicles containing DNA
d. a and b
e. all of the above

e

One of the advantages of fluorescence microscopy is that investigators can use the technique on _____ cells.
a. living
b. dead
c. round
d. very large
e. very small

a

Which of the following sites within a cell are places where microtubules are found?
a. mitotic spindle
b. ciliary core
c. nucleoplasm
d. a and b
e. a, b, and c (nucleoplasm has intermediate filaments in the lamins)

d

The microtubule wall is composed of globular proteins arranged in longitudinal rows called _________. (page 971-972) in the book
a. microfilaments
b. protofilaments
c. prototubules
d. prototubulins
e. microtubular units

b

In a normal microtubule, how many protofilaments make up its cylindrical wall?
a. 13
b. 15
c. 11
d. 9
e. 17

a

What kind of forces are thought to hold microtubular structure together?
a. strong interactions
b. noncovalent interactions
c. covalent interactions
d. a and c
e. all of the above

b

The dimers that assemble to form a microtubule are ________.
a. homodimers
b. heterodimers-Beta and alpha
c. alpha-tubulins
d. beta-tunulins
e. b and c

b

Which end of a microtubule is the fast growing end?
a. the plus end
b. tubulin at the tip probably sposed to be alpha and beta tubulin, which the plus end i think involves beta on the plus end
c. tubulin at the tip
d. the minus end
e. a and b

a

MAPs are microtubule-associated proteins. What role are they thought to play with respect to microtubules?
a. They increase microtubule stability.
b. They decrease microtubule stability.
c. They promote microtubule assembly.
d. They promote microtubule disassembly.
e. a and c

e

The activity of various MAPs is controlled mostly by the ______ of phosphate groups from particular amino acid residues by ________. pg 1080 and pg 1001
a. addition, protein kinases
b. addition, phosphatases
c. removal, protein kinases
d. removal, phosphatases
e. a and d

a

An abnormally high level of ______ of the MAP protein tau is implicated in the development of strange, tangled filaments called _________ that have been seen in the brains of patients suffering from several fatal neurodegenerative diseases like Alzheimer's disease.
a. phosphorylation, neurofibrillary tangles
b. phosphorylation, neurofibrillary anastomoses
c. dephosphorylation, neurofibrillary tangles
d. dephosphorylation, neurofibrillary anastomoses
e. amination, neurofibrillary tangles

a

Which of the following is a function of microtubules?
a. They provide mechanical support for cells.
b. They help to maintain cell shape.
c. They are skeletal elements in certain highly elongated cellular processes like axons.
d. They form most of the structure of centrioles.
e. all of the above

e

Cells that have a _________ shape have microtubules that __________.
a. columnar; are oriented with their long axis parallel to the long axis of the cell
b. columnar; are oriented with their long axis perpendicular to the long axis of the cell
c. rounded, flattened shape; extend in a radial array outward from the area around the nucleus
d. rounded, flattened shape; extend in a radial array inward from the area around the nucleus
e. a and c

e

What happens to axons growing out from a neuron when they are exposed to colchicine or nocodazole and why does this happen?
a. Axons grow more rapidly. The drugs disrupt microtubule growth.
b. Axonal outgrowth stops. The drugs disrupt microtubule growth.
c. Axons grow more rapidly. The drugs enhance microtubule growth.
d. Axonal outgrowth stops. The drugs enhance microtubule growth.
e. There is no change in axonal outgrowth. The drugs disrupt microtubule growth.

b

How are microtubules thought to affect cell shape in plants?
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.
e. none of the above

e

You are performing an experiment on a cultured animal cell and observing the Golgi complex as part of your study. You add a drug to the cultured cells and when you do, the elements of the Golgi complex disperse into the cell periphery. When the drug is removed, the Golgi membranes return to their normal position in the cell interior. What drug was likely to have been used?
a. actinomycin D
b. colchicine
c. nocodazole
d. aspirin
e. b and c

e.

You are performing an experiment on a cultured animal cell and observing the Golgi complex as part of your study. You add colchicine to the cultured cells and when you do, the elements of the Golgi complex disperse into the cell periphery. When colchicine is removed, the Golgi membranes return to their normal position in the cell interior. What conclusion would you draw from this result?
a. The correct positioning of the Golgi complex is dependent upon microfilaments.
b. The correct positioning of the Golgi complex is dependent upon microtubules.
c. The correct positioning of the Golgi complex is dependent upon intermediate filaments.
d. Colchicine kills the cell.
e. Colchicine binds to the Golgi complex and disperses it.

b

In what form are proteins and neurotransmitters usually transported down the axon of a nerve cell?
a. individually by diffusion
b. in groups of ten
c. inside transport vesicles
d. inside the Golgi complex

c

Structures that move from the cell body of a neuron down the axon toward the neuron terminals are said to move in a(n) _________ direction.
a. retrograde
b. anterograde
c. astronomical
d. radial

b

The movement of endocytic vesicles formed in the neuron terminals from the synapse to the cell body is said to be in a(n) ________ direction.
a. retrograde
b. anterograde
c. astronomical
d. radial
e. intergrade

a

Which of the following is known to be transported at one time or another by molecular motors?
a. synaptic vesicles
b. mitochondria
c. chromosomes
d. lysosomes
e. all of the above

e

Which of the following is a family of molecular motors?
a. myosins
b. kinesins
c. dyneins
d. motorins
e. a, b and c

e

Which of the following serve as tracks for molecular motors?
a. intermediate filaments
b. microtubules
c. microfilaments
d. a, b and c
e. b and c

e

Which of the following molecular motors is associated with microtubules?
a. kinesins
b. dyneins
c. myosins
d. a and b
e. a, b and c

d

Which of the following molecular motors is associated with microfilaments?
a. kinesins
b. dyneins
c. myosins
d. a and b
e. a, b and c

c

Which of the following molecular motors is associated with intermediate filaments?
a. kinesins
b. dyneins
c. myosins
d. none of the other answers
e. a, b and c

d

Which of the following molecular motors is known to travel in a retrograde direction along microtubules?
a. kinesins
b. dyneins
c. myosins
d. a and b
e. a, b and c

b

Which of the following molecular motors is known to travel in an anterograde direction along microtubules?
a. kinesins
b. dyneins
c. myosins
d. a and b
e. a, b and c

a

What is the minimum number of kinesin heads in contact with a microtubule at all times?
a. 0
b. 1
c. 2
d. 3
e. 4

b

The heads of kinesin-like proteins have fairly closely related amino acid sequences but diverse tail sequences. What is the explanation for this seeming contradiction?
a. The similarity of kinesin-like protein heads and the variation in their tails are purely random.
b. The similarity of the heads is explained by their similar roles in interacting with microtubules; the variation in the tails reflects the variety of cargoes to which they bind.
c. The similarity of the heads is explained by their different roles in interacting with microtubules; the variation in the tails reflects the similar cargoes to which they bind.
d. The similarity of the heads is explained by their similar roles in interacting with microtubules; the variation in the tails reflects the similar cargoes to which they bind.
e. The similarity of the heads is explained by their different roles in interacting with microtubules; the variation in the tails reflects the variety of cargoes to which they bind.

b

What is the direct source of energy that powers molecular motors?
a. hydrolysis of GTP
b. hydrolysis of ATP - the book says they function like GTPases, but ATP is used (fig 16-60 pg. 1015)
c. proton gradient
d. H+ gradient
e. condensation of ATP

b

What part of the molecular motor kinesin is responsible for binding to the cargo to be hauled?
a. the motor domain
b. the neck
c. the rodlike stalk
d. the fan-shaped tail
e. all of the above

d

Microscopic beads are coated with kinesin and subjected to an in vitro mobility assay. In which direction and along what cytoskeletal element are they seen to move?
a. toward the plus end of the microtubule
b. toward the plus end of the microfilament
c. toward the minus end of the microtubule
d. toward the minus end of the microfilament
e. toward the plus end of the intermediate filament

a

Kinesin movement along a microtubule is said to be ________ meaning that it can move long distances along an individual microtubule without falling off.
a. excessive
b. processive
c. depressive
d. progressive
e. egressive

b

Each step that kinesin makes along a microtubule is about 8 nm. How many tubulin subunits correspond to this distance?
a. 1
b. 3
c. 4
d. 2
e. 5

d

The heads of kinesin-like proteins have fairly closely related amino acid sequences but diverse tail sequences. What is the explanation for this seeming contradiction?
a. The similarity of kinesin-like protein heads and the variation in their tails are purely random.
b. The similarity of the heads is explained by their similar roles in interacting with microtubules; the variation in the tails reflects the variety of cargoes to which they bind.
c. The similarity of the heads is explained by their different roles in interacting with microtubules; the variation in the tails reflects the similar cargoes to which they bind.
d. The similarity of the heads is explained by their similar roles in interacting with microtubules; the variation in the tails reflects the similar cargoes to which they bind.
e. The similarity of the heads is explained by their different roles in interacting with microtubules; the variation in the tails reflects the variety of cargoes to which they bind.
A small subfamily of kinesins moves toward the minus end of a microtubule, while the rest move toward the plus end

b

A small subfamily of kinesins moves toward the minus end of a microtubule, while the rest move toward the plus end. When the neck and stalk of a plus-directed kinesin is joined to the head of a minus-directed kinesin, in what direction will the hybrid motor protein travel along a microtubule?
a. toward the minus-end of the microtubule
b. in a retrograde direction
c. toward the plus-end of the microtubule
d. in an anterograde direction
e. c and d

e

Cytoplasmic dynein moves __________ in a __________ direction.
a. regressively, retrograde
b. processively, anterograde
c. processively, retrograde
d. retrogradely, processive
e. hurriedly, anterograde

c

Cytoplasmic dynein moves ________.
a. organelles down the axon toward the cell body
b. organelles down the axon toward the synapse
c. lysosomes from the cell periphery to the cell center
d. endosomes from the cell center toward the cell periphery
e. a and c

e

Cytoplasmic dynein requires a multisubunit adaptor called _______ to bind its cargo. It cannot bind its cargo directly. This adaptor may also regulate dynein activity and help bind the motor protein to the microtubule.
a. dynactin
b. dynamin
c. stratin
d. dyneinactin
e. didactin

a

The slower phase of microtubule assembly in which a small portion of the microtubule is initially formed is called
___________.
a. elongation
b. nucleation
c. centrosome
d. translation
e. insulation

b

There is a variety of specialized cellular structures that direct the polymerization of microtubules, the best studied one of which is the centrosome. The general name of these structures is _________.
a. microtubule-organizing centers
b. MTOCs
c. a and b
d. nucleus
e. mitochondrion

b

The structure that contains two barrel-shaped centrioles surrounded by amorphous, electron-dense pericentriolar material is called a(n) _________.
a. centrosome
b. nucleus
c. pericentriosome
d. spindle
e. aster

a

What word below describes the arrangement of microtubules in a centriole?
a. doublet
b. triplet
c. pinwheel
d. perpendicular
e. b and c (both)

e

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