The Cytoskeleton Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Three classes of filaments

A

Actin
Interm mediate filaments
Microtubules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is f-actin, what is it made of

A

Filamentous actin

Made of G actin (globular actin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Actin structure

A

Polarised double helix
Diameter= 7nm
13 subunits per turn

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Actin filament growth

A

ATP hydrolysis to ADP as soon as incorporation occurs
Removed or added from both ends
Added more rapidly to +ve end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Actin functions

A

1, mechanical support

  1. Cell shape changes/maintenance
  2. Cell motility
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Intermediate filament structure

A

Polymers of individual IF proteins

10nm in diameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

IF location and function

A

Most dense around nucleus, extends to periphery

Anchor cell at cell junction
Support nuclear structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

IF growth

A

2 IF protein -> helical dimer
2 helical dimmers-> 1 tetramer (fundamental unit)
Tetramers link -> Staggered formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What links IF to actin and microtubules

A

Plectin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Microtubule structure

A
Stiff hollow tube of 13 tubulin monomers
Diameter= 25nm 
Rapidly assembles & disassembled 
Alpha and beta tubulin 
Has polarity (one end has alpha; other end beta)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Growth of microtubule

A

GTP-> GDP : removal of monomers from -ve end

GDP-> GTP: addition of monomers to +ve end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where are microtubules polymerised

A

In centrosomes.
-ve end stays close to centrosome
+ve end points towards cell periphery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Examples of how actin affects cell shape and orientation

A

Dense sheets of actin in cell cortex

  1. Microvilli
  2. RBC
  3. stereocilia: actin keeps stereocilia rigid-> cells are polarised/depolarised by deflections caused by sound
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Example of how IF affects cell shape and orientation

A

Stabilises axon shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Example of how microtubules affect cell shape and orientation

A

Platelets/axons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Example of how actin anchors organelles

A

Holds synaptic vesicles near presynaptic membrane

17
Q

Example of how microtubules anchor organelles

A

They organise ER

18
Q

Actin-based cell movement

A
  1. Actin filament polymerisation-> cell protrusion
  2. focal contact junctions allow adherence between surface cell is moving through and F actin
  3. Cell pulls against anchorage points to drag itself forward
  4. Depolymerisation at rear
19
Q

Lamellopodia mechanism/function

A

Made from rapid growth of actin
+ve end towards periphery
Attachment to extracellular, matrix by focal adhesions

Exploratory and motile
Samples environment
Extends and withdraws

20
Q

Interaction between myosin and actin that allow for cell movement

A
  1. ATP attaches to myosin-> myosin binds to actin
  2. ATP hydrolysed -> myosin tail moves
  3. ADP released-> myosin head detaches
  4. ATP reattaches-> head binds further down actin
21
Q

Microtubule based movement and associated protein

A

Cilia/flagella
9+2 arrangement of microtubules

Dynein: minus-end directed motor protein

22
Q

Example of how microtubules move intracellular contents/organelles

A

Microtubules move synaptic vesicles along axons to synapses
2 associated motor-proteins…
Kinesin: moves towards +ve end (cell periphery)
Dynein: moves towards -ve end (near nucleus)

Cell div

23
Q

Kinesin features

A

Processive motor protein-> attached to microtubule throughout

Movement requires ATP

10cm per day

24
Q

Examples of chemotherapeutic agents that disrupt cytoskeleton. How do they do so

A

Vinblastine/colchicine/taxol
V+c destabilise microtubules
Taxol stabilises microtubules

All 3 inhibit mitosis spindle and cell division

25
Q

2 examples of actin-related cytoskeleton diseases

A
  1. Mutations in dystrophin -> duchenne and Becker muscular dystrophy
  2. mutations in myosin VII-> ushers syndrome (deafness and blindness)
26
Q

2 examples of IF-related diseases

A
  1. Mutations in keratin-> blistering/sloughing-> Epidermolysis bullosa symplex
  2. Mutations in meurofilamin genes -> ALS
27
Q

2 examples of microtubule-related disease

A
  1. Alzheimer’s: neurofibrillary tangles-> Tau is hyperphosphorylated-> can’t bind microtubules
  2. Hereditary spastic paraplegia: mutations in spastin (severs microtubules)
28
Q

Listeria bacteria mechanism

A

Listeria engulfed-> escapes phagocytic vesicle-> f actin polymerised at back of bacterium-> bacterium comet-ed into neighbouring cell