Cytoskeleton Flashcards

1
Q

Families of protein filaments

A
  • Actin filaments
  • microtubules
  • intermediate filaments
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2
Q

shape of the cell’s surface; whole-cell locomotion; pinching of one cell into two

A

Actin filaments

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3
Q

positions of membrane enclosed organelles; direct intracellular transport; from the mitotic spindle

A

Microtubules

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4
Q

mechanical strength

A

intermediate filaments

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5
Q
  • underlie the plasma membrane of animal cells
  • strength and shape to its thin lipid bilayer
A

Actin Filaments

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6
Q

Types Cell surface projections formed by actin filaments

A
  • filopodia
  • lamellipodia
  • pseudopodia
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7
Q

on the surface of hair cells in the inner ear contain stable bundles of actin filaments that tilt as rigid rods in response to sound

A

Stereocilia

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8
Q

on the surface of intestinal epithelial cells vastly increase the apical cell-surface area to enhance nutrient absorption

A

Microvilli

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9
Q

Where can microtubles be found?

A

In cytoplasmic array that extend to cell periphery

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10
Q
  • found in cytoplasmic array that extends to the cell periphery
  • form a bipolar mitotic spindle during cell division
A

Microtubules

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11
Q

What does microtubules form?

A

Cilia

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12
Q

motile whips or sensory devices

A

Cilia

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13
Q
  • line the inner face of the nuclear envelope
  • protective cage for the cell’s DNA
A

Intermediate filaments

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14
Q

twisted into strong cables that can hold epithelial cells sheet together.

A

intermediate filaments in cytosol

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15
Q

An important and dramatic example of rapid reorganization of the cytoskeleton occurs during

A

Cell division

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16
Q

bipolar mitotic spindle

A

Interphase microtubules

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17
Q

crawl across the surface of the dish

A

Actin

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18
Q

belt around the middle of the cell; pinch the cell into two

A

Contractile ring

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19
Q

protrusive structure filled with newly polymerized actin filaments

A

Neutrophils

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20
Q

The cells that have achieved a stable, differentiated morphology

A

Mature neurons or epithelial cells

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21
Q

cytoskeletal-based cell surface protrusions including microvilli and cilia are able to maintain a ____ ____

A

constant location

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22
Q

use organized arrays of microtubules, actin filaments, and intermediate filaments to maintain the critical differences between the apical surface and the basolateral surface

A

Polarized epithelial cells

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23
Q

Subunits for actin filaments; ATP hydrolysis

A

actin subunits

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24
Q

subunits for microtubules; GTP hydrolysis

A

Microtubules

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25
Q

are made up of subunits that are themselves elongated and fibrous

A

intermediate filaments

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26
Q
  • determine the spatial distribution and the dynamic behavior of the filaments
  • bind to the filaments or their subunits to determine the sites of
    assembly of new filaments
  • bring cytoskeletal structure under the control of extracellular and intracellular signals
  • maintain a highly organized but flexible internal structure
A

accessory proteins

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27
Q
  • bind to a polarized cytoskeletal filament
  • energy from ATP hydrolysis to move along the filament, and the “cargo” they carry
  • carry membrane enclosed organelles
  • cause cytoskeletal filaments to exert tension or to slide against each other
A

motor proteins

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28
Q

tubulin homolog that forms Z-ring

A

FtsZ

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29
Q

actin homolog

A

MreB and Mbl

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30
Q

bacterial actin homolog;
encoded by a gene on certain bacterial plasmids that also carry genes responsible for antibiotic resistance

A

ParM

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31
Q

harbors a protein with significant structural similarity to intermediate filaments

A

Caulobacter crescentus (italicized)

32
Q

a protein that forms a filamentous structure that influences the unusual crescent shape of this species

A

Crescentin

33
Q

assembly of actin subunits

A

head-to-tail

34
Q

types of Different ends

A
  • Minus end
  • plus end
35
Q

a slower growing minus end

A

Pointed end

36
Q

faster-growing plus end

A

Barbed end

37
Q

the minimum length at which random thermal fluctuations are likely to cause it to bend

A

Persistence length

38
Q

control their shape and movement

A

Regulation of actin filament formation

39
Q

subunits assemble into an initial aggregate, or nucleus, that is
stabilized by multiple subunit–subunit
contacts and can then elongate rapidly by
addition of more subunits

A

nuceloation

40
Q

lag period; G-actin aggregates into short, unstable oligomers; when oligomers reaches a certain length, it can act as a stable seed or nucleus

A

Nucleation

41
Q

rapidly increases in length by the addition of actin monomers to both of its ends

A

Elongation

42
Q

G-actin monomers exchange with subunits at the filament ends, but there is no net change in the total mass of filaments

A

Steady-state

43
Q

called when steady-state phase has been reached, the concentration of the pool of unassembled subunits

A

Critical concentration, Cc

44
Q

the ratio of the “on”and “off” rate constant

A

Dissociation constant

45
Q

manifested by the different rates at which G-actin adds to the two end

A

Polarity of F-actin

46
Q

decorated actin filaments nucleate the polymerization of G-actin

A

Myosin

47
Q

caused by a difference in Cc values at the two ends

A

DIfference of elongation filament

48
Q

Cc is about six times ____ for polymeration at (+) end than addition at the (-) end

A

lower

49
Q

G-actin concentrations intermediate between the Cc values for the (+) and the (-) end

A

Stead-state phase

50
Q

regulates the actin behavior, that bind actin monmers or filaments

A

Accessory proteins

51
Q

a measure of how long an individual actin monomer spends in a filament as it treadmills

A

Filament half-life

52
Q

inhibition of actin polymerization; they cannot associated with either the plus or minus ends; neither hydrolyze nor exchange their bound nucleotide

A

Thymosin

53
Q

binds to the face of the actin monomer opposite the ATP-binding cleft, blocking the side of the monomer that would normally associate with the filament minus end

A

Profilin

54
Q

prerequisite for cellular actin polymerization

A

Filament nucleation

55
Q

actin-related proteins

A

Arp 2/3 complex

56
Q

dimeric proteins that nucleate the growth of straight, unbranched filaments that can be cross-linked by other proteins to form parallel bundles

A

Formins

57
Q

side-binding proteins; elongated protein that binds simultaneously to six or seven adjacent actin subunits

A

Tropomyosin

58
Q

binds at the plus end; stabilizes an actin filament (inactive)

A

Capping protein (CapZ)

59
Q
  • capping long-lived actin filaments in muscle; minus end-binding
  • binds tightly to the minus ends that have been coated and stabilized by tropomyosin
  • reduce their elongation and depolymerization
A

Tropomodulin

60
Q
  • are activated by high levels of cytosolic Ca2+
A

Gelsolin superfamily

61
Q

interacts with the side of the actin filament and contains subdomains that bind to two different sites

A

Gelsolin

62
Q
  • actin depolymerizing factor;
  • binds along the length of the actin filament, forcing the filament to twist a little more tightl
A

Cofilin

63
Q

cross-link actin filaments into parallel array

A

Bundling proteins

64
Q

hold two actin filaments together at a large angle to each other, forming a looser meshwork

A

Gel-forming proteins

65
Q

enable stress fiber and other contractile arrays to contract
- an elongated protein formed from two heavy chains and two copies of each light chains

A

Myosin II

66
Q

close packing of actin filaments; not contractile

A

Fimbrin

67
Q

cross-links oppositely polarized actin filaments into loose bundle; allowing the binding of myosin and formation of contractile actin bundles

A

α-actinin

68
Q

formation of a loose and highly viscous gel; by clamping together two actin filaments roughly at right angles

A

Filamin

69
Q

observed in migrating fibroblasts. These are filled with dense cores of filamentous actin

A

Lamellipodia

70
Q

defect in nerve-cell migration during early embryonic development

A

filamin A gene mutations

71
Q

periventricular region of the brain fail to migrate to the cortex and instead form nodules

A

Periventricular heteropia

72
Q

web-forming; long, flexible protein made out of four elongated polypeptide chains

A

Spectrin

73
Q

first motor protein identified

A

Skeletal muscle myosin

74
Q

globular head domain at its N-terminus. contains force-generating machine

A

Heavy chain

75
Q

– bind close to the N-terminal head

A

Light chains

76
Q
A