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Cell Biology > W9 Cytoskeleton and Motility > Flashcards

W9 Cytoskeleton and Motility Flashcards

1
Q

what is the cytoskeleton

A

a network of interconnected filaments and tubules

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2
Q

what’s the function of the cytoskeleton

A

cell structure and mechanics

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3
Q

what are the 3 major structural elements
make up the cytoskeleton

A

microfilaments
intermediate filaments
microtubules

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4
Q

what are microfilaments made of

A

coiled-coil chain of actin monomers

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5
Q

how small are microfilaments

A

7nm

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6
Q

what are the main job function of microfilaments

A

muscle contraction
cell migration

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7
Q

what are the monomers of F-actin microfilaments

A

polymerized G-Actin

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8
Q

what are intermediate filaments made of

A

8 overlapping protofilaments

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9
Q

do microfilaments have polarity

A

yes

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10
Q

do intermediate filaments have polarity

A

no

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11
Q

what’s the role of intermediate filaments

A

structural support for animal cell shape

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12
Q

what are intermediate filaments the most at

A

the most stable
the most diverse
the most insoluble

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13
Q

how are intermediate filaments assembled

A

2 polypeptides intertwined into a coiled-coil

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14
Q

what are 2 examples of intermediate filaments

A

desmin
keratin

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15
Q

what are microtubules made of

A

hollow tube of 13 protofilaments

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16
Q

what is the main job of the microtubules

A

chromosome movement

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17
Q

what are the 2 microtubules

A
  • cytoplasmic microtubules
  • axonemal microtubules
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18
Q

what’s the functions of cytoplasmic microtubules

A

regulation of cell shape
vesicle transport
axon formation
mitotic spindle formation

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19
Q

what’s the function of axonemal microtubules

A

cell mobility

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20
Q

how are actin filaments regulated

A

binding proteins

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21
Q

what does profilin do

A

binds ATP actin and promotes polymerisation

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22
Q

what does thymosin do

A

binds ATP actin and blocks polymerisation

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23
Q

what does formins do

A

bind actin filaments and promote elongation

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24
Q

what does Arp2/3 do

A

promotes nucleation and branching

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25
Q

where do microtubules get fromed

A

centrosome

26
Q

how are microtubules made

A
  • tubulin dimers are formed into oligomers in the nucleation step
  • during elongation phase more tubulins are added to ends of microtubules
  • at the plateau stage tubulins will treadmill
27
Q

what is critical concentration for microtubules

A

tubulin concentration needs to be above the critical concentration for microtubule growth

28
Q

what is treadmilling of microtubules

A

adding subunits at plus end
removing subunits at minus end

29
Q

what is microtubule dynamic instability

A

populations of MTs will undergo polymerization and depolymerization simultaneously

30
Q

what is microtubule catastrophe

A

switch from growth to shrinkage

31
Q

what is microtubule rescue

A

switch from shrinkage to growth

32
Q

what’s the role of GTP in microtubules

A

provides energy for MT growth

33
Q

what are MT stabilizing proteins called

A

tau proteins

34
Q

what are MT destabilizing proteins called

A

stathmin

35
Q

how is the cytoskeleton linked

A

integrin and cadherin

36
Q

what do cadherin receptors do

A

bind onto adjacent cells

37
Q

what do adherents junctions do

A

link to F-actin microfilaments

38
Q

what do desmosomes do

A

link intermediate filaments

39
Q

how do eukaryotes mobility systems work

A

interactions between motor proteins and microtubules
interactions between myosin proteins and mcirofilament

40
Q

how does Microtubule-based movement work

A

kinesins or dynein move along microtubules

41
Q

what are kinesins made of

A
  • globular head that attaches to MT
  • coiled helical region
  • light chain region
42
Q

how do kinesins move

A

using ATP the “foots” will move along the MT

43
Q

how do dynein motor proteins work

A

heavy chain and dynactin complex bind and move along MT

44
Q

how do cilia and flagella move

A

ATP hydrolysis of dynein proteins

45
Q

what are myosins

A

tetramers which are ATP-dependant motors

46
Q

how does myosin move

A

globular heads bind to actin and move towards plus end

47
Q

what are myofibrils made of

A

sarcomeres

48
Q

what are thick filaments

A

bundles of myosin

49
Q

what are thin filaments

A

F-actin intertwined with tropomyosin and troponin

50
Q

what causes muscle contraction

A

release of Ca2+ to bind myosin head to myosin binding site on actin

51
Q

what are 2 examples of actin based motility

A

cytokinesis and endocytosis

52
Q

how to cells crawl

A

extend protrusions

53
Q

how do cells extend protrusions

A

actin polymerisation so acto-myosin contractility can happen

54
Q

how do amoebas and white blood cells migrate

A

amoeboid movement

55
Q

what is amoeboid movement

A

protrusions of pseudopodium

56
Q

what is pseudopodia

A

depolymerized F-actin

57
Q

which type of migration is faster amoeboid or extended protrusions

A

amoeboid movement

58
Q

how can we prevent amoeboid migration for cancer cells

A

myosin inhibition
block metastasis

59
Q

what’s the importance of fast amoeboid movement

A

immune responses

60
Q

what does GTP cap do for cytoskeleton

A

allows tubulin to add to microtubules without falling off

Cell Biology (11 decks)

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