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Cell Bio > 2-cell anatomy: cytoskeleton > Flashcards

2-cell anatomy: cytoskeleton Flashcards

1
Q

the cytoskeleton can form ________ and can be ____ and _____

A

stable structures
dynamic
adaptable

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2
Q

the cytoskeleton is involved in numerous processes related to ______, ______, and ______

A

shape
support
locomotion

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3
Q

3 main types of protein filaments

A
  1. microtubules
  2. actin filaments
  3. intermediate filaments
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4
Q

_______ regulate filament assembly and dynamics

A

cytoskeletal associated proteins (accessory factors)

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5
Q

cytoskeleton general properties:

A
  1. filaments self assemble from small subunits
  2. subunits associations with a filament are weak and noncovalent
  3. filaments consist of multiple protofilaments that associate laterally with each other which allows for overall thermal stability for filaments
  4. accessory proteins regulate assembly of new filaments
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6
Q

breaking a filament in the middle requires breaking sets of _____ in several protofilaments. This results in overall _________ for the filaments

A

longitudinal bonds
thermal stability

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7
Q

removing a subunit from the ends requires less energy, leaving the filament ends as _________

A

dynamic structures

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8
Q

what are microfilaments composed of

A

globular actin monomer

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9
Q

MF: actin monomers bind

A

ATP

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10
Q

MF: actin monomers assemble to form

A

a filament

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11
Q

MF: 2 parallel _____ twist around each other to form a ___________

A

protofilaments
right handed helix

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12
Q

MF: actin subunits assemble _____ to ____ and generate filaments with a distinct ______

A

head to tail
polarity

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13
Q

MF: filaments “grow” from the _____ end

A

plus

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14
Q

MF: actin filaments are ________ and ______

A

relatively flexible and easily bent

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15
Q

MF: in living cells, accessory proteins crosslink and bundle MFs together to create __________ actin structures much _____ than individual MFs

A

large-scale
stronger

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16
Q

localization of MFs

A

-MFs are often concentrated near the cell periphery
-Actin filaments are also observed running the length of cells

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17
Q

main roles of MFs determine the ___________ and to facilitate__________

A

shape of the cell’s surface
whole cell locomotion

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18
Q

Microtubules (MT) made up of:

A

-globular tubulin subunits
-tubulin monomers bind GTP
-alpha nad beta tubulin monomers form tubulin heterodimers
-protofilament is composed of alternating alpha and beta tubulin

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19
Q

MTs: cylinder structure

A

13 protofilaments build the MT cylinder
Cylinder is long and hollow

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20
Q

MT has an associated _______ .

A

polarity
- subunits point in one direction
-protofilaments are parallel
-growing end =plus end

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21
Q

the multiple contacts in the MT lattice make MT __________

A

stiff and difficult to bend

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22
Q

MT localization:

A

-nucleation occurs at the MTOC
-MTOC anchors and protects minus end of growing filament
-in animal cells, centrosome is near the nucleus
-from the MTOC, the MTs emanate in a star like conformation often out to the cell periphery

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23
Q

the main role of MTs:

A

determine the positions of membrane enclosed organelles and to direct intracellular transport

24
Q

IFs structure:

A

-heterogenous family of rope-like filaments
-assembled from distinct subunits (inc. keratins, neurofilaments, vimentin-like proteins, lamins)
-does not contain an associated nucleotide (NTP)

25
Q

IFs: are made by:

A

-elongated alpha helical monomeric subunits dimerize and then associate to form staggered tetrameric subunits
-tetramers pack together to form protofilament
-filament formed from 8 parallel protofilaments
-non-polar
-easily bent but hard to break

26
Q

IFs localization:

A

-IFs provide strength to cells and tissues
-in general, IFs are prominent in cells that are subject to mechanical stress

27
Q

main role of IFs

A

provide mechanical strength and provide shape to cells and help resist pulling forces

28
Q

_______ are a diverse population of proteins that bind to filaments or subunits to control filament behavior and organization

A

accessory proteins

29
Q

accessory proteins can:

A

1 . crosslink or bundle filaments
2. nucleate filament polymerization
3. cap and block polymerization
4. sever filaments

30
Q

motor proteins overview:

A

-unique cytoskeleton binding protein -function to move molecules and membrane enclosed organelles throughout cell
-can be used to generate force required to move filaments

31
Q

molecular motors convert energy from _____ into _______ to _______

A

ATP hydrolysis
mechanical force
‘walk’ along MF and MT filaments

32
Q

what are the 3 major families of motor proteins:

A
  1. myosin
  2. kinesin
  3. dynein
33
Q

what is the associated filament for myosin

A

microfilaments (actin)

34
Q

what is the associated filament for kinesin ?

A

microtubules

35
Q

what is the associated filament for dynein

A

microtubules

36
Q

what direction does myosin go

A

POS

37
Q

what direction does kinesin go

A

POS

38
Q

what direction does dynein go

A

NEG

39
Q

motor proteins associate with filament tracks via what?

A

a “head” region, or motor domain

40
Q

what does the head region of motor proteins do?

A

binds and hydrolyzes ATP

41
Q

what does the tail region do of motor proteins

A

contains the binding site for cargo

42
Q

which molecular motor is the largest and fastest

A

dynein

43
Q

in kinesin, the binding/hydrolysis of ATP by the head/motor domains _________

A

changes the conformation of the protein which allows kinesin to “walk” or “step” down the MT towards the plus end

44
Q

for dynein, nucleotide hydrolysis is coupled to _____

A

MT bindning and unbinding as well to a force-generating conformational change

45
Q

dynein’s power stroke is driven by the _______

A

binding and hydrolysis of ATP which causes the motor head to rotate relative to the tail

46
Q

what is the function of kinesins

A

-bring cargo to the periphery of the cell
-organelle positioning
-axonal transport
-mitosis

47
Q

what is the function of dyneins?

A

-bring cargo to the periphery of the cell
-cilia/flagella beating
-vesicle transport
-mitosis

48
Q

clinical relevance of cytoskeleton

A

disruption of filament structure and dynamics is associated with many disease pathologies

49
Q

example of mutation in actin binding protein, dystophin

A

canine x lined muscular dystrophy

50
Q

mutations in a range of actin/actin associated proteins are observed in patients with

A

cardiomyopathy

51
Q

_____ binds and stabilizes microtubules

A

taxol

52
Q

cilia structure

A

9 sets of MT doublets and center pair of MTs (9+2)
dynein motors

53
Q

microfilaments are made of what subunits

A

actin

54
Q

microtubules are made of what subunit

A

tubulin

55
Q

intermediate filaments are made of what

A

keratin, neurofilaments, vimentin, lamin

Cell Bio (17 decks)

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