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Cell Biology > Cytoskeleton > Flashcards

Cytoskeleton Flashcards

1
Q

What is the order of cytoskletal components in order from largest to smallest?

A

microtubules, intermediate filaments, actin filaments/microfilaments

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2
Q

Which cytoskeleton component is made of alpha and beta tubulin subunits?

A

microtubules

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3
Q

What are the subunits of microtubules?

A

alpha and beta tubulin

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4
Q

Which cytoskeletal component might be involved in the positioning of the nucleus within the cell

A

microtubules

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5
Q

Which cytoskeletal component might be involved in the mechanical strength of an epithelial cell?

A

intermediate filaments

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6
Q

Which cytoskeletal component provides the shape of the overall cell structure?

A

actin/microfilaments

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7
Q

Which statement about the cytoskeleton is not true? A) cytoskeletal component assemble and disassemble often, making them quite dynamic structures B) many cytoskletal components provide movement and mechanical strength for/to a cell C) some cytoskeletal components are composed of many monomeric subunits D) the various components of the cytoskeleton are held together by a mixture of strong ionic and covalent bonds, giving them their characteristic strength

A

(D) noncovalent bonds hold together the subunits, allowing for the dynamism of the cytoskeleton

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8
Q

The cytoskeleton is a very dynamic structure. What are two benefits/significances of this?

A

1) small subunits can quickly change cellular position 2) allows for a rapid change in cell morphology (e.g. cell migration)

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9
Q

What are the basic subunits of microfilaments?

A

globular proteins called G-actin, which polymerize to form actin filaments (F-actin)

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10
Q

Which end of the actin filament has more ability to grow and shrink (more “dynamic”)?

A

the + end

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11
Q

Platelets change cell shape and form protrusions during blood

clotting. This process involves extensive rearrangement of which cytoskeletal component in particular?

A

actin filament

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12
Q

T or F: Both microtubules and actin filaments have polarity.

A

True

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13
Q

What are “MAP’s” in the context of the cytoskelton?

A

microtubule associated protein- stabilize and organize MT’s

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14
Q

If a cell were to experience a mutation in its microtubules, which of the following functions would you expect to be altered?

A) mitosis

B) cell morphology

C) muscle contraction

D) cellular transportation

E) A and B

F) A, C and D

G) A and D

H) all of the above

A

(G); all of the other options apply to actin filaments

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15
Q

When you hear “microtubules” what functions should you be thinking of?

A

Movement (e.g. cell movement, mitosis, organelle orientation, cell trasport)

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16
Q

MT can grow and shrink at both ends. The oscillation between growth and shortening of MT is called _____ .

A

dynamic instability

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17
Q

Under certain conditions, a filament adds subunits at one

end, and simultaneously loses subunits at the other end. The

net flux of subunits at the two ends is known as

_____.

A

treadmilling

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18
Q

What is treadmilling, in the context of the cytoskeleton?

A

when a filament adds subunits at one

end, and simultaneously loses subunits at the other end (gives a movement like appearance)

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19
Q

An absence of catastrophin would most likely lead to which of the following outcomes for microtubules (MT)?

A) stabilization of the MT, resulting in longer, less dynamic MT’s

B) stabilization of the MT, resulting in shorter, more dynamic MT’s

C) destabilization of the MT, resulting in shorter, more dynamic microtubules

D)

destabilization of the MT, resulting in longer, more dynamic microtubules

A

(C); think: “catastrophin” destabilizes, and destabilization leads to shorter and thus more stable MT’s

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20
Q

Some compounds can disrupt microtubule dynamics and have application in biochemical studies (e.g. anti-cancer drugs). What are 2 examples?

A

1) cochine- prevents assembly of MT
2) taxol- prevents disassembly of MT

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21
Q

Taxol is a compound that tightly binds to ß-tubulin in assembled microtubulues and prevents disassembly of microtubules. Why might this be a good cancer drug?

A

MT’s must be able to disassemble for the cell to divide. Therefore, preventing their disassembly could prevent cancer cells from dividing.

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22
Q

What is the MTOC?

A

microtubule organizing center (centrosome)

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23
Q

In some eukaryotic cells, MTOC’s, in addition to being found in the centrosome, can be found in _____ that are associated with cilium or flagellum

A

basal bodies

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24
Q

MT are arranged in a way that all the ___(negative or positive)___ ends located/pointed at the MTOC.

A

negative

25
Q

The chapter on intracellular transport and cytoskeleton overlap when it comes to vesicular transport. How do they do so?

A

vesicular transport is made possible via the cytoskeleton, namely the MT’s which create a sort of “highway” for the movement of intracellular material

26
Q

What are the two types of motor proteins? Whats the basic difference between the two?

A

1) dyneins- move cargo toward (-)
2) kinesins- move cargo to (+); most MP’s are these

Think: “kinesiology” is

27
Q

Which of the following about intermediate filaments is NOT true?

A) they exist in various forms and are expressed in different cells

B) they are organized into bundles and meshorks by various IF associated proteins

C) they are the most unstable, or dynamic, of the cytoskeletal components

D) they form rope-like filaments assembled from different protein subunits by lateral binding and twisting

A

(C); they are relatively stable cf to MT and AF (though they are still dynamic)

28
Q

What are two broad categories into which intermediate filaments can be placed?

A

1) cytoplasmic
2) nuclear

29
Q

Cytoplasmic intermediate filaments have 3 subcategories. What are they?

A

1) keratins
2) vimentin (and related)
3) neruofilaments

30
Q

Nuclear intermediate filaments can be found in all animal cells. What is the more specific name for these types of intermediate filaments?

A

nuclear lamins

31
Q

How do the subunits of intermediate filaments differ from microtubules and actin filaments?

A

IF’s are assembled to rope-like bundles from helical proteins, not globular

32
Q

IF’s are cross-linked with other components of cytoskeleton by various structures called _____

A

IF Associated Proteins (IFAP).

33
Q

What are IF Associated Proteins (IFAP)?

A

IF’s are cross-linked with other components of cytoskeleton by various IF Associated Proteins (IFAP).

34
Q

What type of microscopy could be used to experimentally show that IF’s are dynamic?

A

Fluorescent-labeling

35
Q

Where would you expect to find the lamins?

A

nucleus

36
Q

If you tried to stretch your skin and it easily split, what cytoskeletal componet is likely missing?

A

intermediate filament (keratin in particular)

37
Q

Which cytoskeleton structures form the mitotic apparatus?

A

microtubules

38
Q

Force is needed to pull apart the chromosomes during mitosis. What two components provide this force?

A

motor proteins (dyneins) and depolymerization of microtubules

39
Q

What process regulates the disassembly and reassembly of intermediate filaments before and after mitosis?

A

phosphorylation

40
Q

What are the “major functions” of actin?

A

1) determine cell shape and polarity (e.g. microvilli)
2) mechanical movement (e.g. muscle contraction)
3) changing cell morphology (e.g. platelets during clotting)
4) regulating cell migration (e.g. platelets during clotting)

41
Q

What is an example of how actin filaments determine cell shape and polarity?

A

microvilli

42
Q

What is an example of how actin filaments participate in mechanical movement?

A

muscle contraction

43
Q

What is an example of how actin filaments change cell morphology and regulate cell migration?

A

platelets during clotting

44
Q

What are the “main functions” of microtubules?

A

1) mitotic activity
2) cell movement
3) intracellular transport

45
Q

What are the “main functions” of intermediate filaments?

A

1) increase mechanical strength (e.g. epithelial cells)
2) provide scaffolding for the nucleus (e.g. “nuclear lamina”)

46
Q

What is the nulcear lamina?

A

a network of intermediate filaments (lamins) located underneath the inner membrane of the nucleus, providing scaffolding for the nuclear structure

47
Q

What are septins?

A

a group of GTP-binding proteins found mostly in eukaryotic cells

48
Q

What is the name of the GTP-binding domain on a septin?

A

G interface

49
Q

What is the G interface

A

the name of the GTP-binding domain on a septin?

50
Q

What is the NC interface?

A

the amino-terminal and carboxy-terminal regions of septin

51
Q

What is the name of the amino‑terminal and carboxy‑terminal regions of septin?

A

NC interface

52
Q

T or F: Although septin subunits are polar, they could assemble end-to-end they form non-polar filaments

A
53
Q

T or F: Abnormal septon expression or function has been associated with Alzheimer’s disease, cancer, and bipolar disorder

A

True

54
Q

What are two functions of septins, with examples of each?

A

scaffold (e.g. restraining membrane bound proteins) and diffusion barriers (e.g. rings of annulus in spermatozoon)

55
Q

In which of the following places would you NOT expect to find the cytoskeleton component septin?

A) the cleavage furrow

B) cilium

C) annulus

D) plasma membrane

E) none of these choices is correct

A

(E); all of these contain septin

56
Q

Which cytoskeleton component provides structural support to the cell?

A

actin/microfilaments

57
Q

Which cytoskeleton component provides strength for cellular structure?

A

intermediate filaments

58
Q
A

Cell Biology (9 decks)

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