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EOM 1 - Test 1 > Lecture 5/6: Cytoskeleton I & II > Flashcards

Lecture 5/6: Cytoskeleton I & II Flashcards

Cytoskeleton I and II

1
Q

Are microtubules easily bent or rigid?

A

Rigid

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2
Q

What is the structure of cilia and flagella?

A

Circumference of 9 pairs of A-tubule/B-tubule complexes, A = complete, B = partial; center 2 complete tubules Hint: 9+2 Structure

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3
Q

What is the role of GTP-tubulin dimer?

A

Adds to + end of microtubules for elongation

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4
Q

What does TAU interact with?

A

Microtubule in the axon

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5
Q

How is actin formed?

A
  1. G-actin forms dimer 2. G-actin forms trimer 3. F-actin is formed
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6
Q

What protein allows contractile actin bundling?

A

alpha-Actinin Hint: Alpha males like contracting muscles

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7
Q

Filamin binds to _____ , and it’s function is ______ .

A

Filaments Cross-links filament networks

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8
Q

What protein transports along microtubules to the Negative end (towards center of cell)?

A

Dynein

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9
Q

Formin binds to _____ , and it’s function is ______ .

A

Monomers Elongates unbranched filaments

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10
Q

Tropmodulin binds to _____ , and it’s function is ______ .

A

Filaments Caps (-) End

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11
Q

What mechanism allows locomotion of cilia and flagella?

A

Dynein armies connected to two of the 9 strands moving to the negative end, creates a falling action

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12
Q

Which is more stable, Intermediate Filaments or Actin?

A

I.F.

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13
Q

What is the basic structure of IF proteins?

A

Cental rod alpha-helix with Head (N) and Tail (C)

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14
Q

What molecule initiates branching in actin filament?

A

Arp2/3

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15
Q

What is the role of Polymerase in Tubulin?

A

Speeds growth

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16
Q

CapZ binds to _____ , and it’s function is ______ .

A

Filaments Caps (+) End

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17
Q

Actin polymerization/depolymerization requires ____.

A

ATP

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18
Q

What are main functions of cytoskeleton within cell?

A

Movement, Signaling, Transporting things in/out Cell

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19
Q

What is the role of CLASP in tubulin?

A

Pauses shrinkage at attachment point

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20
Q

What are cilia and flagella connected to at the negative end?

A

Anchored to Basal Body

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21
Q

What is the energy source for: 1. Actin 2. Microtubules

A
  1. Actin - ATP 2. Microtubules - GTP
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22
Q

What is the pathway (3-substances) for actin branching formation?

A

Rho – > WASP – > Arp2/3

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23
Q

Where are lamins found?

A

Nuclear lamina of all cell types

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24
Q

WASP/Scar binds to _____ , and it’s function is ______ .

A

Arp2/3 Activates Arp 2/3 (branching!)

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25
Q

What is one source for disease such as Alzheimers?

A

TAU proteins falling off, leading to degraded microtubules, and tangled clumps of TAU proteins

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26
Q

What can a defect in the WAS protein result in?

A

Inability for actin branching, bleeding disorders, juvenile death

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27
Q

What material do microtubules form in?

A

Pericentriolar Material

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28
Q

What is the basic structure of Microtubules?

A

Beta-tubulin / Alpha-tubulin subunits combined with GTP with a +/- end, often anchored at - end in cells

29
Q

alpha-Actin binds to _____ , and it’s function is ______ .

A

Filaments Connects two filaments in bundle (contraction)

30
Q

What molecule initiates cleavage of actin filaments? (preventing binding)

A

ADF/Cofillin Hint: After ADF/Cofillin, you will have CO-actins (2x)

31
Q

Where is Epidermolysis Bullosa Simplex (EBS) localized?

A

Epidermis

32
Q

In what direction to microtubules extend in the cell?

A

Negative end anchored to centrosome, grow with positive end extending out

33
Q

What is the role of Dynein?

A

Transport to negative end Hint: Dining In the Center

34
Q

Profillin binds to _____ , and it’s function is ______ .

A

Monomers Stimulates filament formation

35
Q

Where are desmins found?

A

Muscle Cells

36
Q

What protein transports along microtubules to the Positive end (towards the outside)?

A

Kinesin I

37
Q

What joins the A/B Tubule complexes in cilia and flagella? What is it’s role in locomotion?

A

Nexin-Link Constrains movement of dynein

38
Q

Are microtubules fixed in length?

A

No, feature dynamic instability–always changing size

39
Q

Arp2/3 binds to _____ , and it’s function is ______ .

A

Filaments Initiates branching

40
Q

Twinfillin binds to _____ , and it’s function is ______ .

A

Monomers Transports monomer to filament

41
Q

What protein caps the positive (+) end of actin? What does this lead to?

A

CapZ Prevents new additions — degradation

42
Q

Relative size of cytoskeletal proteins?

A

Actin - 7 nm Intermediate - 10 nm Microtubules - 25 nm

43
Q

ADF/Cofillin binds to _____ , and it’s function is ______ .

A

Filaments Dissociates and severs filaments

44
Q

What molecule initiates actin filament formation? What if it stays attached?

A

Formin Hint: Take Formin to get Actin Forming If attached inhibits nucleation

45
Q

Due to their dynamic instability, what enzymes assist microtubules?

A

Polymerase - Speeds Growth Depolymerase - Catastrophic Shrinkage CLASP - Pauses Shrinkage at given length

46
Q

Rho binds to _____ , and it’s function is ______ .

A

WASP Activates WASP (branching!)

47
Q

Dysfunction causing: 1. JEB 2. DEB 3. EBS

A
  1. Lamina V 2. Collagen VII 3. Keratin
48
Q

Where are microtubules found in the nerve cell? What are their differences? What are their stabilizing proteins?

A

Axon - organized - to + leading away from cell, stabilized by TAU protein Dendrites - randomly organized +/-, stabilized by MAP2 protein

49
Q

What is the role of Kinesin I?

A

Transport to the positive end Hint: K is a twisted + sign

50
Q

What are the steps of cell migration?

A
  1. Extension of leading edge (dipping toes in water) 2. Attachment to substrate 3. Retraction of trailing edge (Igor leg drag)
51
Q

What protein stabilizes (connects) actin filament networks?

A

Filamin Hint: Networks–like Collagen IV Hint 2: Fill’em’in

52
Q

What is the role of the basal body?

A

Anchors cilia and flagella

53
Q

What is the role of γ-tubulin ring complex? ( γ-tubulinRC) What is this similar to in actin? Where is it found?

A

Binds at negative end, initiates formation. Similar to Formin in Actin Only seen in centrosome

54
Q

What six proteins regulate actin filament organization?

A
  1. Filament Stabilizing 2. Capping. 3. Severing (cleavage) 4. Cross-Link 5. Polymerizing/Depolymerizing 6. ATP-ADP Exchange Protein
55
Q

What end is added to in actin? Removed? What is this property termed?

A

Add to POSITIVE (+) end — BARBED Remove from NEGATIVE (-) end – POINTED Termed POLARITY

56
Q

How are IF proteins assembled? How are sections added?

A

Polypeptide - Parallel Dimer - Anti-parallel tetramer - Protofilament No +/- like Actin, added to both ends

57
Q

What protein caps the negative (-) end of actin? What does this lead to?

A

Tropomodulin Prevents removal – elongation

58
Q

What is the rate limiting step in polymerization of G-actin to F-actin?

A

Nucleation

59
Q

What protein stabilizes (connects) parallel actin filaments?

A

Fimbrin

60
Q

Fimbrin binds to _____ , and it’s function is ______ .

A

Filaments Connects parallel filaments

61
Q

What affect do various cancer drugs have on microtubules?

A

Either freeze their growth or blocks tubulin for growth

62
Q

What regulates Actin monomers binding to filaments?

A

Profillin

63
Q

Where are keratins found?

A

Epithelial Cells

64
Q

What are the two classes and examples of microtubule projections from the cell?

A
  1. Cilia - tracheal epithelial cells, paramecium 2. Flagella - sperm tail
65
Q

What are two important structures for locomotion in a nerve cell?

A

Filopodia – actin filaments Lamellipodia – actin bundles Hint: Filo – First Foot Filaments Lamel - Camel’s carrying bundles

66
Q

What molecule converts ADP-actin to ATP-actin? What does this stimulate?

A

Profilin , stimulates filament formation Hint: proFILLING up the ATP gas-tank

67
Q

What is the role of Depolymerase in Tubulin?

A

Speeds Shrinkage

68
Q

What does MAP2 interact with?

A

Stabilizes Microtubule in the dendrite

EOM 1 - Test 1 (16 decks)

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