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Histology - Exam #1 > Histology Lecture 7: Cytoskeleton > Flashcards

Histology Lecture 7: Cytoskeleton Flashcards

1
Q

Actin Microfilaments

A

highly conserved among eukaryotes; 7 nm thick; up to 7 micrometers in length; organized into bundles and 3D networks; bind to specific transmembrane proteins either directly or indirectly (via catenins);

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2
Q

What is roughly the length/width of a eukaryotic cell

A

7 micrometers

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3
Q

First step in actin polymerization

A

nucleation

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4
Q

the growing end of the actin microfilament

A

plus or barbed end

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5
Q

actin microfilament; grows 5-10 times faster than the other end

A

barbed/plus/growing end

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6
Q

where the rate of addition of new G-actin to actin filaments occurs more rapidly and at a lower concentration

A

barbed/plus/growing end

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7
Q

slower growing end of the microfilament

A

minus/pointed end

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8
Q

favored by low concentrations of G-actin

A

disassembly at plus/barbed/growing end

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9
Q

the dynamic equilibrium between the minus end and the plus end that is favored by intermediate concentrations of G-actin

A

treadmilling

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10
Q

favored by higher concentrations of G-actin

A

net addition at both ends, and therefore, growth of the actin filament

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11
Q

the dynamic balance between the polymerizing and depolymerizing ends of F-actin

A

treadmilling

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12
Q

bind to barbed ends of actin to block elongation

A

cytochalasins

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13
Q

binds to actin filaments and prevents dissociation; prevents depolymerization by binding to actin filaments

A

phalloidin

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14
Q

responsible for the diversity of function of actin filaments in different regions of the cell

A

actin-binding proteins

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15
Q

actin binding protein that binds cortical cytoskeleton to the plasma membrane and is found in RBCs

A

spectrin

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16
Q

actin binding protein that binds cortical cytoskeleton to the plasma membrane and is found in muscle cells; a defective version will lead to muscular dystrophy

A

dystrophin

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17
Q

actin binding protein that cross-links microvilli; hold together the core of the microvillus [2 answers]

A

villin and fimbrin

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18
Q

actin binding protein that cross links actin to the plasma membrane in microvilli

A

Calmodulin and Myosin I

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19
Q

actin binding protein that forms the cap of the fast growing barbed ends of F actin and promotes the elongation of unbranched F-actin

A

Formin

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20
Q

actin binding protein that regulates the assembly of unbranched actin in cell protrusions, such as the intestinal microvilli, while remaining attached to the end of the barbed end

A

Formin

21
Q

actin binding protein that cross links stress fibers and connects actin to protein-plasma membrane complex complexes

A

alpha-actinin

22
Q

actin binding protein that cross links actin at wide angles to form screen-like gels

A

Filamin

23
Q

actin binding protein that captures actin monomers and prevents actin monomers from being polymerized by sequestering pools of G-actin monomers within cells, thereby regulating treadmilling by keeping monomers out of circulation

A

Thymosin

24
Q

actin binding protein that suppresses nucleation of G-actin and promotes F-actin growth at the barbed end

A

Profilin

25
Q

actin binding protein that can favor the assembly of monomeric G-actin into filaments by facilitating the exchange of bound ADP for ATP

A

Profilin

26
Q

actin binding protein that destabilizes F-actin and caps actin filaments, preventing loss or addition of G-actin

A

Gelsolin

27
Q

actin binding protein that, in the presence of Calcium ion, will fragment actin filaments and remain bound to the barbed end, forming a cap that prevents further filament growth

A

Gelsolin

28
Q

actin binding protein that triggers depolymerization of ADP-bound actin at the minus end; also known as actin depolymerizing factor

A

Cofilin

29
Q

actin binding protein that initiates growth of G-actin from the sides of existing filament and causes branching; actin nucleating complex of 7 proteins; intiates the branch of F-actin

A

Arp2/3

30
Q

binds to G-actin and induces F-actin depolymerization

A

Latrunculins

31
Q

8-10 nm thick; abundant in cells subject to mechanical stress; provide tensile strength in cells; desmosomes and hemidesmosomes; central alpha-helical rod flanked by head and tail domains

A

intermediate filaments

32
Q

dimers associate in a staggered antiparallel fashion to form tetramers and lose polarity in the process; more stable than actin and do not demonstrate dynamic behaviour

A

intermediate filaments

33
Q

associated with other cytoskeletal elements to form a scaffolding that organizes the internal structure of the cell

A

intermediate filaments

34
Q

25 micrometers in diameter; alpha and beta tubulin monomers form tubulin dimers; protofilaments are longitudinal rows of tubulin dimers;

A

microtubules

35
Q

consist of 13 protofilaments arranged parallel to form a cyclinder with a hollow core; exhibit polarity (fast growing plus end and slow growin minus end)

A

microtubules

36
Q

1) two polypeptides form a coiled dimer
2) dimers associate in a staggered antiparallel fashion to form tetramers
3) tetramers assemble end to end to form protofilaments
4) eight protofilaments are wound together to form filaments

A

Intermediate Filament Assembly

37
Q

microtubules; grows more rapidly than minus end in the presence of low calcium ion concentrations

A

plus end

38
Q

end of a microtubule associated with tubulin dimers with GTP bound to the Beta-tubulin

A

growing end

39
Q

condition by which microtubule tubulin dimers are added more rapidly than GTP is hydrolyzed thereby favoring growth of the microtubule

A

high concentrations of tubulin-GTP

40
Q

condition by which GTP at the plus end is hydrolyze and dimers are lost, favoring depolymerization

A

low concentrations of tubulin-GTP

41
Q

the polymerization-to-depolymerization transition frequency

A

catastrophe

42
Q

the depolymerization-to-polymerization transition frequency

A

rescue

43
Q

inhibit microtubule polymerization; anti-cancer drug used in the treatment of Hodgkins lymphoma

A

Vinblastin

44
Q

stabilizes microtubules; anti-cancer drug used in the treatment of breast cancer

A

taxol

45
Q

mediates transport of cargo towards the plus end of a microtubule (anterograde transport)

A

kinesin

46
Q

mediates transport of cargo towards the minus end of a microtubule (retrograde transport)

A

cytoplasmic dynein

47
Q

motor protein with only one head (other three have 2 heads)

A

Myosin I

48
Q

motor protein whose head moves towards the minus end (other three move towards the plus end)

A

cytoplasmic dynein

Histology - Exam #1 (9 decks)

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