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
are made up of subunits that are themselves elongated and fibrous
intermediate filaments
26
* 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
accessory proteins
27
* 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
motor proteins
28
tubulin homolog that forms Z-ring
FtsZ
29
actin homolog
MreB and Mbl
30
bacterial actin homolog; encoded by a gene on certain bacterial plasmids that also carry genes responsible for antibiotic resistance
ParM
31
harbors a protein with significant structural similarity to intermediate filaments
Caulobacter crescentus (italicized)
32
a protein that forms a filamentous structure that influences the unusual crescent shape of this species
Crescentin
33
assembly of actin subunits
head-to-tail
34
types of Different ends
- Minus end - plus end
35
a slower growing minus end
Pointed end
36
faster-growing plus end
Barbed end
37
the minimum length at which random thermal fluctuations are likely to cause it to bend
Persistence length
38
control their shape and movement
Regulation of actin filament formation
39
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
nuceloation
40
lag period; G-actin aggregates into short, unstable oligomers; when oligomers reaches a certain length, it can act as a stable seed or nucleus
Nucleation
41
rapidly increases in length by the addition of actin monomers to both of its ends
Elongation
42
G-actin monomers exchange with subunits at the filament ends, but there is no net change in the total mass of filaments
Steady-state
43
called when steady-state phase has been reached, the concentration of the pool of unassembled subunits
Critical concentration, Cc
44
the ratio of the “on”and “off” rate constant
Dissociation constant
45
manifested by the different rates at which G-actin adds to the two end
Polarity of F-actin
46
decorated actin filaments nucleate the polymerization of G-actin
Myosin
47
caused by a difference in Cc values at the two ends
DIfference of elongation filament
48
Cc is about six times ____ for polymeration at (+) end than addition at the (-) end
lower
49
G-actin concentrations intermediate between the Cc values for the (+) and the (-) end
Stead-state phase
50
regulates the actin behavior, that bind actin monmers or filaments
Accessory proteins
51
a measure of how long an individual actin monomer spends in a filament as it treadmills
Filament half-life
52
inhibition of actin polymerization; they cannot associated with either the plus or minus ends; neither hydrolyze nor exchange their bound nucleotide
Thymosin
53
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
Profilin
54
prerequisite for cellular actin polymerization
Filament nucleation
55
actin-related proteins
Arp 2/3 complex
56
dimeric proteins that nucleate the growth of straight, unbranched filaments that can be cross-linked by other proteins to form parallel bundles
Formins
57
side-binding proteins; elongated protein that binds simultaneously to six or seven adjacent actin subunits
Tropomyosin
58
binds at the plus end; stabilizes an actin filament (inactive)
Capping protein (CapZ)
59
- 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
Tropomodulin
60
- are activated by high levels of cytosolic Ca2+
Gelsolin superfamily
61
interacts with the side of the actin filament and contains subdomains that bind to two different sites
Gelsolin
62
- actin depolymerizing factor; - binds along the length of the actin filament, forcing the filament to twist a little more tightl
Cofilin
63
cross-link actin filaments into parallel array
Bundling proteins
64
hold two actin filaments together at a large angle to each other, forming a looser meshwork
Gel-forming proteins
65
enable stress fiber and other contractile arrays to contract - an elongated protein formed from two heavy chains and two copies of each light chains
Myosin II
66
close packing of actin filaments; not contractile
Fimbrin
67
cross-links oppositely polarized actin filaments into loose bundle; allowing the binding of myosin and formation of contractile actin bundles
α-actinin
68
formation of a loose and highly viscous gel; by clamping together two actin filaments roughly at right angles
Filamin
69
observed in migrating fibroblasts. These are filled with dense cores of filamentous actin
Lamellipodia
70
defect in nerve-cell migration during early embryonic development
filamin A gene mutations
71
periventricular region of the brain fail to migrate to the cortex and instead form nodules
Periventricular heteropia
72
web-forming; long, flexible protein made out of four elongated polypeptide chains
Spectrin
73
first motor protein identified
Skeletal muscle myosin
74
globular head domain at its N-terminus. contains force-generating machine
Heavy chain
75
– bind close to the N-terminal head
Light chains
76