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Cell Bio And Histology > Cytoskeleton > Flashcards

Cytoskeleton Flashcards

0
Q

Name some functions of the cytoskeleton…

A

Forms the scaffolding to define shape,
Involved in cell division and movement,
Distribute forces between cells, adjacent cells, and the basal lamina,
Cytokinesis,
Phagocytosis,
Cell to cell and cell to EC matrix adherence

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1
Q

The cytoskeleton is composed of three subunits known as the?…

A

Microfilaments, intermediate filaments, and microtubules

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2
Q

Microfilaments are made up of?…

A

Actin

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3
Q

Mammals have six actin genes. Where are they expressed?

A

4-muscle cells

2-non muscle cells

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4
Q

What gives rod shaped bacteria their structure?

A

Mreb (prokaryotic ancestor of Actin)

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5
Q

What does it mean for Actin to be highly conserved in evolution?

A

Doesn’t change from cell to cell.

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6
Q

Actin exists as…

A

G actin monomers. That form F actin chains

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7
Q

What are the three major varieties of Actin?

A

Alpha (expressed in muscle)

Beta and gamma (expressed in non muscle)

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8
Q

Low concentrations of G actin favor?…

A

Disassembly of actin filaments

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9
Q

High concentrations of G actin favor?…

A

Net additions at both ends and results in growth of the actin filament.

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10
Q

Describe treadmilling.

A

Intermediate concentrations favor a dynamic equilibrium between the (+) (-) ends resulting in zero net growth.

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11
Q

G actin exists in two forms

A

ATP bound and ADP bound

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12
Q

Found in the Red Sea sponge, this actin binding protein blocks elongation, binds to the barbed (+) end, and inhibits movements of the cell-mitosis

A

Cytochalasins

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13
Q

Found in mushrooms; this actin binding protein can be used in fluorescent dyes to visualize actin, and bind to actin filaments to prevent dissociation.

A

Phalloidin

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14
Q

There are many many actin binding proteins found in the human body and carry special functions. This particular protein can be found in red blood cells and it binds cortical cytoskeleton to the plasma membrane. Known to several to be a ghost. Oooooooohhhhh!!!!

A

Spectrin

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15
Q

One of the largest actin binding proteins that also bind cortical cytoskeleton to the PM. Associated with Duchennes and Beckers muscular dystrophy.

A

Dystrophin

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16
Q

Two of the actin binding proteins that cross link in microvilli are?…

A

Villin and fimbrin

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17
Q

Calmodulin and myosin 1 function how?

A

They cross link actin to the plasma membrane in microvilli

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18
Q

This type of actin binding protein cross links actin at wide angles forming a screen like gel.

A

Filamin

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19
Q

Cross links stress fibers and connects actin to protein plasma membrane complexes.

A

Alpha actinin

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20
Q

Sequesters G actin monomers and prevents polymerization.

A

Thymosin

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21
Q

Binds ATP bound G actin monomers to the barbed end of the helical actin filament chain and controls the rate of polymerization

22
Q

Destabilizes F actin and prevents loss or addition of G actin by capping. In the presence of calcium, it fragments the filament.

23
Q

Triggers depolymerization of ADP bound actin at the pointed (-) end.

24
Initiates growth of F actin from the sides of existing filament-causing it to branch. *Think of the kind of insurance old people get.*
Arp 2/3 (AARP) get it?
25
This term describes the rate limiting step requiring the correct alignment of the first three monomers.
Nucleation
26
These large dimers bind initial monomers and move along the growing filament as monomers are added
Formin
27
T/F: Formin and ARP 2/3 determine where filaments are formed by facilitating nucleation
True
28
Forming nucleate long unbranched actin filaments, many if which are stabilized by?
Tropomyosins. Also found in skeletal muscle
29
Derived from fungi, they bind to G actin and induce F actin depolymerization
Latrunculins
30
Small rigid proteins with at least two domains that bind actin and align filaments closely with one another.
Cross link proteins
31
What are the two types of actin bundling proteins?
Parallel and contractile
32
Contractile bundles are cross liked by?...
Alpha actinin. Makes sense since it is found in muscle cells
33
This type of cytoskeletal feature, roughly 8-10nm thick, have a common monomer consisting of an alpha helical rod flanked by head and tail domains. Provides strength to cells in neurons and muscle.
Intermediate filaments
34
Intermediate filaments are formed by rod like proteins consisting of repeating amino acid sequence called a?...
Heptad
35
What are the five intermediate filament associated proteins?
``` Flaggerin, epinemin, paranemin, plectin, synemin ```
36
What major role do intermediate filaments play?
Stabilize filaments by cross linking adjacent filaments or by linking to other cytoskeletal elements
37
T/F intermediate filament assembly requires ATP or GTP
False. Requires neither. Forms spontaneously
38
What are the type 1 intermediate filaments?
Acidic keratins- form the intermediate filaments of the epithelial cell cytoskeleton and associated with plaques of desmosomes and hemidesmosomes.
39
What are the type 2 Intermediate filaments
Neutral or basic keratins. They help type 1.
40
There are four subunits of type 3 intermediate filaments. What are they and where are they found?
Vimentin- mesenchymal cells Desmin- sarcomeric Z disks in muscle Glial fibrillary acidic protein- astrocytes and Schwann cells (glial cells) Peripherin- associated with neurofilaments
41
Type 4 intermediate filaments are found?...
Neurofilaments- found in axons and dendrites
42
Type 5 intermediate filaments are the Nuclear lamins. What do they provide? ....this is getting old quick.
Mechanical support for inner membrane of nuclear envelope and bind chromatin
43
And lastly, type 6. Thank god. It's Nestin. What does it associate with?
CNS stem cells
44
They consist of 13 protofilaments arranged in parallel to form a cylinder with a hollow core.
Microtubules
45
Protofilaments are longitudinal rows of Tubulin dimers consisting of...
Alpha + beta unit
46
What does MAPs stand for?
Microtubule associated proteins
47
Chemotherapeutic factor that stabilizes microtubules
Taxol
48
Drugs that inhibit microtubules polymerization
Colchicines Vincristine Vinblastine Colcemid
49
How are cilium arranged structurally?
9 peripheral doublets + central pair of microtubules 9+2 arrangement
50
Each doublet consorts of?...
Alpha tubule and a beta tubule
51
Alpha tubules are comprised of (#?) protofilaments which extend to sheath around the central pair
13
52
Beta tubules have (#?) protofilaments angled towards the plus end
10-11

Cell Bio And Histology (17 decks)

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