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Immunology > Cytoskeletal System > Flashcards

Cytoskeletal System Flashcards

1
Q

Cytoskeleton

A

It is a network of interconnected filaments and tubules extending through the cytosol
-It plays roles in cell movement and division
-It is dynamic and changeable
-Cell interior is highly structured

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2
Q

Cytoplasmic microtubules

A

-Maintaining axons
-Formation of mitotic and meiotic spindles
-Maintaining or altering cell shape
-Placement and movement of vesicles
-Orientation of cellulose microfibrils during plant cell wall growth

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3
Q

Axonemal microtubules

A

-Includes the organised and stable microtubules found in structures such as:
-Cilia
-Flagella
-Basal bodies to which cilia and flagela attach
-The axoneme, the central shaft of a cilium or flagellum, is a highly ordered bundle of MTs

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4
Q

Microtubule structure

A

-Beta tubulin will always be N-terminal end that has a plus end
-Alpha tubulin will always be a C-terminal end that has a negative charge

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5
Q

rate-limitng step of microtubules

A

formation of dimers is slowest steps

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6
Q

Microtubule assembling

A
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7
Q

Microtubule Treadmiling

A

+ and - ends have different critical concentrations
-Treadmiling: addition of subunits at the plus end, and removal from the minus end ( constant elongation and shortening)

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8
Q

Dynamic instability model

A

One population of MTs grows by polymerisation at the plus ends, whereas another population shrinks by depolymerisation at the plus ends
-GTP gives stability and when there is no GTP, the dimer breaks down at plus end which is known as catastrophe

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9
Q

Catastrophe

A

-Individual MTs can go through periods of growth and shrinkage; a switch from growth to shrinkage

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10
Q

rescue

A

A sudden switch back to growth phase

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11
Q

Catastrophe and rescue graph

A
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12
Q

MTOC

A

Microtubule organising center
-Gamma tubulin binds to gamma-TuRC and stabilises Mt

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13
Q

MTOC distribution

A

Anaphase I- Centrosome
Basal body

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14
Q

Centrosomes

A

Composed of a triplet arrangement with 9 triplet microtubules being used to make a centriole

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15
Q

Colchicine, colcemid

A

Binds B-tubulin
-inhibitng assembly

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16
Q

Nocadazole

A

Binds beta-tubulin which inhibits polymerisation

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17
Q

Vinblastine, vincristine

A

Aggregates tubulin heterodimers

18
Q

Paclitaxel (taxol)

A

Stabilises microtubules
-Uses up all tubulin causing cell to die because there is no movement

19
Q

MTOC different cells

A

Nerves
Ciliated epithelial
RBC

20
Q

Mt regulation

A

-great precision
-Mt-binding proteins use ATP to drive vesicle or organelle transport or to generate sliding forces between MTs
-Others regulate Mt structure

21
Q

Microfilament functions

A

-Smallest filaments
1. Muscle contraction
2. Cell migration, amoeboid movement and cytoplasmic streaming
3. Maintenance of cell shape
4. Structural core microvilli
5. Cleavage furrow production during cytokinesis

22
Q

G-actin

A

globular actin
single protein
gives rise to f-actin
-Has to be ATP-bound to be attached to filament

23
Q

F-actin

A

Filamentous actin
multiple G-actins bound together to form MF (polymerised)
-2 F-actin eind together to form MF

24
Q

Isoforms

A

alpha-actin-muscular
Beta-actin
gamma-actin

25
Q

Polarity of MF

A

Polarity is reflected in more rapid addition or loss of G-actin at plus end than minus end
-After the G-actin monomers assemble onto MF, the ATP bound to them is slowly hydrolysed
-So growing MF ends have ATP-actin whereas most of MF is composed of ADP-actin

26
Q

Architecture of Actin in crawling cells

A

-Rapid moving cells dont have stress fibers
-The cell cortex, just beneath the plasma membrane, has actin crosslinked into a gel of MF

27
Q

Stress fibers

A

Cells that adhere tightly to underlying substratum have organised bundles called stress fibers
-found in contractile bundle

28
Q

Cell cortex

A

gel

29
Q

Lamelllpodium

A

Branched network

30
Q

Flipodium

A

Parallel bundle

31
Q

Actin binding proteins

A

Control where and how actin assembles into MF

32
Q

Filament formation binding proteins

A

Monomer sequestering proteins prevent formation (thymosin)
-Actin polymerising proteins cause formation (formin)

33
Q

Filament lenght binding proteins

A

filament-severing proteins (gelsolin)
Filament-capping proteins (CapZ)

34
Q

Filament organisation actin binding proteins

A

Filament-crosslinking proteins (filamin)
Filament-bundling proteins ( alpha-actin, fibrinin)

35
Q

Drugsthat affect stability of MFs

A
36
Q

Intermediate filaments

A

Most stable
least soluble
likely support entire cytoskeleton
IF proteins are tissue specific
-Keratin is NB component of structures that grow on skin in animals

37
Q

classes of IF

A
38
Q

IF formation

A
39
Q

Drugs that affect IF stability

A

Acrylamide- Causes loss of intermediate filament networks (carcinogenic)

40
Q

IF functions

A
41
Q

Critical concentration

A

The tubular heterodimer concentration at which MT assembly is exactly balanced with disassembly

Immunology (7 decks)

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