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BIOL340 > The Cytoskeleton > Flashcards

The Cytoskeleton Flashcards

1
Q

the cytoskeleton provides strength and shape, playing a central role in movement and division by driving and guiding intracellular ???

A

organelle traffic

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2
Q

Microtobulues are hollow or solid tubes?

A

hollow

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3
Q

microtubules are formed from ??? dimers and are 25nm big

A

tubulin

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4
Q

microfilaments are a double helix made of ??? monomers and are about 7nm big

A

actin

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5
Q

intermediated filaments are a strong fibre composed of ??? subunits and are 8-12nm big

A

protein

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6
Q

what is an example of the cytoskeleton’s ability to rapidly reorganise?

A

a fibroblast

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7
Q

TRUE or FALSE: the cytoskeleton is responsible for large-scale cellular polarity which allows cells to tell the difference between top, bottom or front and back

A

TRUE

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8
Q

what is the largest structural element of the cytoskeleton?

A

microtubules

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9
Q

microtubules are rigid and typically have one end attached to a ???

A

microtubule-organising centre

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10
Q

cytoplasmic microtubules pervade the cytosol and are responsible for maintaining/altering cell shape, placement and movement of vesicles, formation of mitotic and meiotic spindles and ???

A

maintaining axons

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11
Q

are axonemal or cytoplasmic microtubules responsible for placement and movement of vesicles?

A

cytoplasmic MTs

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12
Q

what part of the cytoskeleton is responsible for the formation of mitotic and meiotic spindles?

A

cytoplasmic Microtubules

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13
Q

axonemal or cytoplasmic Microtubules include he organised and stable microtubules in structures such as cilia/flagella and the basal bodies to which they attach

A

axonemal

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14
Q

the basic subunit of a microtubule protofilament is a heterodimer of ???

A

tubulin

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15
Q

microtubules are composed of one alpha tubulin and one beta-tubulin bound COVALENTLY or NON-COVALENTLY to each other?

A

non-covalently

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16
Q

are all the dimers of microtubules or intermediate filaments oriented the same way?

A

microtubules

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17
Q

how do microtubule protofilaments have an inherent polarity?

A

because of dimer orientation

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18
Q

microtubules are hollow cylindrical structures built from 13 parallel ??? of tubulin protein

A

protofilaments

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19
Q

microtubules will self-assemble in-vitro but ??? is the rate limiting step

A

nucleation

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20
Q

nucleation of microtubules creates a ring structured microtubule seed for growth but this is slow. More commonly seeded by ??? ring in microtubule organising centre to be speedier

A

gamma-tubulin ring

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21
Q

microtubules originate from ??? within the cell. Centrosomes near the nucleus and basal bodies near the cell membrane in cilia/flagella

A

microtubule-organising centres

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22
Q

microtubules grow outwards from microtubule-organising centres with a fixed polarity where the MINUS or PLUS (?) ends are anchored in the MTOC

A

minus ends

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23
Q

dynamic growth and shrinkage of microtubules occurs at the PLUS or MINUS end?

A

plus

24
Q

MTs form by the reversible polymerisation of dimers in the presence of ??? and Mg2+

A

GTP

25
Q

what is a unique property of microtubules?

A

their ability to constantly polymerise and depolymerise i.e. dynamic instability

26
Q

microtubule binding proteins modulate filament dynamics and ??? and can also mediate the interaction of microtubules with other cell components. i.e. tau proteins

A

organisation

27
Q

microtubule targeting agents interfere with ??? and alter equilibrium between subunits

A

tubulin assembly/disassembly

28
Q

TRUE or FALSE: Disruption of microtubules induces various cellular responses often
leading to cell cycle arrest or cell death

A

True

29
Q

an example of a microtubule targeting agent is ??? which comes from a yew tree and binds along filaments to stabilise them

A

taxol (paclitaxel)

30
Q

an example of a microtubule targeting agent is ??? which comes from an autumn crocus and caps both filament ends to depolymerise the microtubule

A

colchicine

31
Q

microtubules allow for nutrient transport in neurons. Tau helps support these microtubules, but hyperphosphorylated Tau forms affrefates, dissociating from MTs and staving the neurons = ???

A

alzheimers

32
Q

Microfilaments are helical polyemers of actin that are flexible and are dispersed throughout the cell but most concentrated in the ??? beneath the plasma membrane

A

cortex

33
Q

microfilaments develop and maintain ??? and are involved in cell migration and cytoplasmic streaming.

A

cell shape

34
Q

what is the structural core of microvilli?

A

microfilaments

35
Q

microfilaments are composed of actin subunits that are a 375-amino-acid polypeptide carrying a tightly associated molecule of ??? or ???

A

ATP or ADP

36
Q

microfilament actin subunits assemble head to tail to form a ???

A

protofilament

37
Q

two microfilament protofilaments form a helix held together by ??? contacts

A

lateral

38
Q

like tubulin, the actin protofilaments composing ??? have polarity and the ends differ chemically and structurally

A

microfilaments

39
Q

Globular‐actin (G-actin) monomers REVERSIBLY or IRREVERSIBLY (?) polymerise into actin microfilaments (“F‐actin”). G‐actin is added rapidly at the plus end and slower/lost at the minus end. G‐actin monomers nucleate slowly but then can assemble onto MF more rapidly, bound ATP is then slowly hydrolysed to ADP. Growing MF ends have ATP‐actin, whereas most of the MF is composed of ADP‐actin

A

reversibly

40
Q

G-actin is added rapidly at the PLUS or MINUS end of a microfilament and slower at the opposite end

A

plus

41
Q

subunits of ??? cycle rapidly between free and filamentous states and have the ability to maintain a constant length despite a net flux of subunits through the polymer

A

microfilaments

42
Q

treadmilling of microfilaments occurs at a subunit concentration where filament growth balances ??? Requires ATP hydrolysis for energy

A

shrinkage

43
Q

what type of energy does treadmilling of actin filaments require?

A

ATP Hydrolysis

44
Q

actin binding proteins influence filament dynamics and organisation. E.g. ??? stimulates filament elongation

A

profilin

45
Q

TRUE or FALSE: the role of microfilaments can be determined through chemical inhibition that can be used to unsettle microfilaments

A

TRUE

46
Q

lactrunculin is a drug that ??? by binding to actin subunits. Originally found from sponges

A

depolymerises

47
Q

cytochalasin B depolymerises actin by capping the filaments ??? ends. comes from fungi

A

plus

48
Q

phalloidin stabilises acting by binding along filaments. Comes from the ???

A

amanita mushroom

49
Q

Mutations in the skeletal muscle α‐actin gene (ACTA1) may affect its ??? binding ability and cause a range of congenital myopathies. People with actin-accumulation myopathy have severe muscle weakness (myopathy) and poor muscle tone (hypotonia) throughout the body
e.g. Floppy baby syndrome

A

ATP

50
Q

intermediate filaments are the most stable component of the cytoskeleton, conferring strength on tissues. they are rope-like fibers with a ??? diameter

A

10nm

51
Q

intermediate filaments are assembled from basic structural units consisting of two intermediate filament ??? intertwined into a coiled-coil

A

polypeptides

52
Q

the two dimers of intermediate filaments are ???

A

aligned in parallel

53
Q

parallel dimers align laterally to form a tetrameric protofilemt which overlap to build a filamentous structure ~8 protofilaments thick. Intermediate filaments or microfilaments?

A

intermediate filaments

54
Q

types of intermediate filaments can be:
- nuclear (lamins)
- Vimentin-like (vimentin, desmin)
- epithelial (???)
- axonal (neurofilament proteins)

A

keratin

55
Q

A single epithelial cell can produce multiple
types of keratins which co‐polymerise into a single network held together by ??? bonds

A

disulfide

56
Q

??? impart mechanical strength by anchoring the intermediate filaments at sites of cell–cell and cell matrix contact – desmosomes and hemidesmosomes

A

keratins

57
Q

epidermolysis bullosa simplex: Occurs when defective keratins are expressed in the ??? of the epidermis. Results in the skin blistering to even mild mechanical stress

A

basal cell layer

BIOL340 (13 decks)

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