Lecture 17 - Cytoskeleton & CM: Motor Proteins Flashcards

1
Q

def: movement of a cell or organism through the environment, movement of the environment past or through the cell, movement of components in the cell

A

cell motility

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2
Q

def: the shortening of muscle cells, and is a specialized form of motility

A

cell contractility

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3
Q

what are the 2 eukaryotic motility systems?

A
  1. interactions between microtubules and motor proteins kinesics and dyenins
  2. interactions between actin microfilaments and members of the myosin motor proteins
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4
Q

motor proteins convert chemical energy into __________ _________

A

mechanical energy

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5
Q

how to molecular motors move?

A

unidirectionally along their cytoskeletal components in a step wise manner

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6
Q

what are the 3 categories of molecular motors?

A
  1. kinesins
  2. dyneins
  3. myosins
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7
Q

what do each of the molecular motors use as tracks?

A

kinesis and dyneins use microtubules and myosin use microfilaments

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8
Q

T or F: motors undergo cycles of ATP hydrolysis, release of ADP + Pi, and acquisition of a new ADP molecule

A

true

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9
Q

do motor proteins have momentum?

A

no, they are subject to tremendous friction

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10
Q

are motors processive?

A

yes they move along a cytoskeletal filament for significant distances

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11
Q

traffic toward the (-) ends of microtubules is considered _____________; toward the (+) end is _______________-

A

inbound and outbound

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12
Q

def: movement of vesicles and organelles along microtubules

A

fast axonemal transport

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13
Q

____________ is involved in ATP-dependent transport toward the plus ends (away from the centrosome), called ____________ ________ ____________

A

Kinesin I, anterograde axonal transport

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14
Q

___________ ______________ moves particles in the opposite direction towards the minus end, called __________ ___________ _____________

A

retrograde axonal transport

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15
Q

what is the size of steps that kinesis move along the microtubules in

A

8 nm

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16
Q

what are the 4 parts of a Kinesin I tetramer?

A
  1. a globular head region that attaches to MTs (act as ATP hydrolyzing engine)
  2. a neck region (connect head to stalk)
  3. a coiled helical stalk region (provide flexibility)
  4. a light chain region (attaches kinesis to proteins, organelles, or other cargo)
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17
Q

KRP tail regions are ________ ___________-

A

highly divergent, reflecting cargo diversity

18
Q

def: moves with HIGH processivity toward the minus ends of microtubules

A

cytoplasmic dyneins

19
Q

does dynein directly interact with cargo?

A

no it requires an adaptor molecule like dynactin and spectrin

20
Q

def: generate motility in the cilia and flagella

A

axonemal dyneins

21
Q

T or F: organelles may bind kinesin and dynein simultaneously with motors engaging in a tug of war type battle for the cargo

A

true

22
Q

def: found in unicellular and multicellular eukaryotes, display an oar-like pattern of beating, generating a force perpendicular to the cilium

A

cilia

23
Q

_________ cilia move fluid through tracts

A

motile

24
Q

____ ______ ______ cilia are thought to have sensory functions

A

non-motile

25
Q

def: move cells through a fluid environment, they are the same diameter as cilia, but usually longer

A

flagella

26
Q

force generated by flagella is ________ to the flagellum

A

parallel

27
Q

what is the common structure shared between cilia and flagella

A

axoneme

28
Q

where do cilium/flagellum emerge from?

A

basal body and surrounded by an extension of the cell membrane

29
Q

between the axoneme and basal body is a __________ ________ in which the microtubules begin to take on the pattern characteristic of the axoneme

A

transition zone

30
Q

the axoneme consists of _______ ________ ________ _________ surrounding a ________ _______ _________ __________

A

nine peripheral microtubule doublets, central pair of single microtubules

31
Q

each microtubule double consists of ?

A
  • 1 complete microtubule
  • 1 incomplete microtubule
32
Q

the central tubules are enclosed by a _________ connected to the peripheral doublets by radial spokes

A

sheath

33
Q

__________ ____________ project from the A microtubule as pairs of “arms”

A

axonemal dyneins

34
Q

what does the assembly and disassembly of cilium and flagellum require?

A

the transport of material to and form the distal tip

35
Q

def: movement of structural components between the peripheral doublets and the cell membrane

A

intraflagellar transport

36
Q

def: pulls the IFT trains towards the cilium/flagellum tip

A

Kinesin-2

37
Q

def: causes microtubule sliding within the axoneme allowing cilia and flagella to bend, there is no change in the overall length of the microtubules

A

axonemal dynein

38
Q

the stem of each axonemal dynein molecule is tightly anchored to the outer surface of the __ __________

A

A tubule

39
Q

def: the presence of this prevents the sliding of the doublets past each other

A

nexin

40
Q

at any given time, what is the status of the axonemal dyneins on either side of the axoneme

A

one side is active while the other is not

41
Q

where are primary cilia used?

A

in sensory structures