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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
What is one source for disease such as Alzheimers?
TAU proteins falling off, leading to degraded microtubules, and tangled clumps of TAU proteins
26
What can a defect in the WAS protein result in?
Inability for actin branching, bleeding disorders, juvenile death
27
What material do microtubules form in?
Pericentriolar Material
28
What is the basic structure of Microtubules?
Beta-tubulin / Alpha-tubulin subunits combined with GTP with a +/- end, often anchored at - end in cells
29
alpha-Actin binds to _____ , and it's function is ______ .
Filaments Connects two filaments in bundle (contraction)
30
What molecule initiates cleavage of actin filaments? (preventing binding)
ADF/Cofillin Hint: After ADF/Cofillin, you will have CO-actins (2x)
31
Where is Epidermolysis Bullosa Simplex (EBS) localized?
Epidermis
32
In what direction to microtubules extend in the cell?
Negative end anchored to centrosome, grow with positive end extending out
33
What is the role of Dynein?
Transport to negative end Hint: Dining In the Center
34
Profillin binds to _____ , and it's function is ______ .
Monomers Stimulates filament formation
35
Where are desmins found?
Muscle Cells
36
What protein transports along microtubules to the Positive end (towards the outside)?
Kinesin I
37
What joins the A/B Tubule complexes in cilia and flagella? What is it's role in locomotion?
Nexin-Link Constrains movement of dynein
38
Are microtubules fixed in length?
No, feature dynamic instability--always changing size
39
Arp2/3 binds to _____ , and it's function is ______ .
Filaments Initiates branching
40
Twinfillin binds to _____ , and it's function is ______ .
Monomers Transports monomer to filament
41
What protein caps the positive (+) end of actin? What does this lead to?
CapZ Prevents new additions --- degradation
42
Relative size of cytoskeletal proteins?
Actin - 7 nm Intermediate - 10 nm Microtubules - 25 nm
43
ADF/Cofillin binds to _____ , and it's function is ______ .
Filaments Dissociates and severs filaments
44
What molecule initiates actin filament formation? What if it stays attached?
Formin Hint: Take Formin to get Actin Forming If attached inhibits nucleation
45
Due to their dynamic instability, what enzymes assist microtubules?
Polymerase - Speeds Growth Depolymerase - Catastrophic Shrinkage CLASP - Pauses Shrinkage at given length
46
Rho binds to _____ , and it's function is ______ .
WASP Activates WASP (branching!)
47
Dysfunction causing: 1. JEB 2. DEB 3. EBS
1. Lamina V 2. Collagen VII 3. Keratin
48
Where are microtubules found in the nerve cell? What are their differences? What are their stabilizing proteins?
Axon - organized - to + leading away from cell, stabilized by TAU protein Dendrites - randomly organized +/-, stabilized by MAP2 protein
49
What is the role of Kinesin I?
Transport to the positive end Hint: K is a twisted + sign
50
What are the steps of cell migration?
1. Extension of leading edge (dipping toes in water) 2. Attachment to substrate 3. Retraction of trailing edge (Igor leg drag)
51
What protein stabilizes (connects) actin filament networks?
Filamin Hint: Networks--like Collagen IV Hint 2: Fill'em'in
52
What is the role of the basal body?
Anchors cilia and flagella
53
What is the role of γ-tubulin ring complex? ( γ-tubulinRC) What is this similar to in actin? Where is it found?
Binds at negative end, initiates formation. Similar to Formin in Actin Only seen in centrosome
54
What six proteins regulate actin filament organization?
1. Filament Stabilizing 2. Capping. 3. Severing (cleavage) 4. Cross-Link 5. Polymerizing/Depolymerizing 6. ATP-ADP Exchange Protein
55
What end is added to in actin? Removed? What is this property termed?
Add to POSITIVE (+) end --- BARBED Remove from NEGATIVE (-) end -- POINTED Termed POLARITY
56
How are IF proteins assembled? How are sections added?
Polypeptide - Parallel Dimer - Anti-parallel tetramer - Protofilament No +/- like Actin, added to both ends
57
What protein caps the negative (-) end of actin? What does this lead to?
Tropomodulin Prevents removal -- elongation
58
What is the rate limiting step in polymerization of G-actin to F-actin?
Nucleation
59
What protein stabilizes (connects) parallel actin filaments?
Fimbrin
60
Fimbrin binds to _____ , and it's function is ______ .
Filaments Connects parallel filaments
61
What affect do various cancer drugs have on microtubules?
Either freeze their growth or blocks tubulin for growth
62
What regulates Actin monomers binding to filaments?
Profillin
63
Where are keratins found?
Epithelial Cells
64
What are the two classes and examples of microtubule projections from the cell?
1. Cilia - tracheal epithelial cells, paramecium 2. Flagella - sperm tail
65
What are two important structures for locomotion in a nerve cell?
Filopodia -- actin filaments Lamellipodia -- actin bundles Hint: Filo -- First Foot Filaments Lamel - Camel's carrying bundles
66
What molecule converts ADP-actin to ATP-actin? What does this stimulate?
Profilin , stimulates filament formation Hint: proFILLING up the ATP gas-tank
67
What is the role of Depolymerase in Tubulin?
Speeds Shrinkage
68
What does MAP2 interact with?
Stabilizes Microtubule in the dendrite

EOM 1 - Test 1 (16 decks)

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