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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
Q

Initiates growth of F actin from the sides of existing filament-causing it to branch.

Think of the kind of insurance old people get.

A

Arp 2/3 (AARP) get it?

25
Q

This term describes the rate limiting step requiring the correct alignment of the first three monomers.

A

Nucleation

26
Q

These large dimers bind initial monomers and move along the growing filament as monomers are added

27
Q

T/F: Formin and ARP 2/3 determine where filaments are formed by facilitating nucleation

28
Q

Forming nucleate long unbranched actin filaments, many if which are stabilized by?

A

Tropomyosins. Also found in skeletal muscle

29
Q

Derived from fungi, they bind to G actin and induce F actin depolymerization

A

Latrunculins

30
Q

Small rigid proteins with at least two domains that bind actin and align filaments closely with one another.

A

Cross link proteins

31
Q

What are the two types of actin bundling proteins?

A

Parallel and contractile

32
Q

Contractile bundles are cross liked by?…

A

Alpha actinin. Makes sense since it is found in muscle cells

33
Q

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.

A

Intermediate filaments

34
Q

Intermediate filaments are formed by rod like proteins consisting of repeating amino acid sequence called a?…

35
Q

What are the five intermediate filament associated proteins?

A 
Flaggerin, 
epinemin, 
paranemin, 
plectin, 
synemin
36
Q

What major role do intermediate filaments play?

A

Stabilize filaments by cross linking adjacent filaments or by linking to other cytoskeletal elements

37
Q

T/F intermediate filament assembly requires ATP or GTP

A

False. Requires neither. Forms spontaneously

38
Q

What are the type 1 intermediate filaments?

A

Acidic keratins- form the intermediate filaments of the epithelial cell cytoskeleton and associated with plaques of desmosomes and hemidesmosomes.

39
Q

What are the type 2 Intermediate filaments

A

Neutral or basic keratins. They help type 1.

40
Q

There are four subunits of type 3 intermediate filaments. What are they and where are they found?

A

Vimentin- mesenchymal cells

Desmin- sarcomeric Z disks in muscle

Glial fibrillary acidic protein- astrocytes and Schwann cells (glial cells)

Peripherin- associated with neurofilaments

41
Q

Type 4 intermediate filaments are found?…

A

Neurofilaments- found in axons and dendrites

42
Q

Type 5 intermediate filaments are the Nuclear lamins. What do they provide?

….this is getting old quick.

A

Mechanical support for inner membrane of nuclear envelope and bind chromatin

43
Q

And lastly, type 6. Thank god. It’s Nestin. What does it associate with?

A

CNS stem cells

44
Q

They consist of 13 protofilaments arranged in parallel to form a cylinder with a hollow core.

A

Microtubules

45
Q

Protofilaments are longitudinal rows of Tubulin dimers consisting of…

A

Alpha + beta unit

46
Q

What does MAPs stand for?

A

Microtubule associated proteins

47
Q

Chemotherapeutic factor that stabilizes microtubules

48
Q

Drugs that inhibit microtubules polymerization

A

Colchicines

Vincristine

Vinblastine

Colcemid

49
Q

How are cilium arranged structurally?

A

9 peripheral doublets + central pair of microtubules

9+2 arrangement

50
Q

Each doublet consorts of?…

A

Alpha tubule and a beta tubule

51
Q

Alpha tubules are comprised of (#?) protofilaments which extend to sheath around the central pair

52
Q

Beta tubules have (#?) protofilaments angled towards the plus end

Cell Bio And Histology (17 decks)

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