Dynamic Cell- JC's

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What does Plectin do?
Links IF, MT and actin cytoskeleton, and associates with the membrane
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What i caused by deficiencies in it?
Epidermolysis bullosa, muscular dystrophy, neurodegeneration
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What family are Cdc42, Rho and Rac part of?
Rho G-protein family
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What role do they each play in the regulation of the cytoskeleton?
Cdc40: polymerisation + bundling (filopodiea and microspikes) Rho: bundling of actin with intern and myosin II- focal contact formation. Rac- polymerisation at the periphery = lamella podia
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Which is the master of cell polarity?
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Name 3 types of cytoplasmic intermediate filaments + where they are found
Keratins (in epithelia), vimentin + vimentin-related (in connective tissue, muscle cells and glial cells), neurofilaments (in nerve cells)
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Name 1 type of nuclear intermediate filament
Nuclear lamins- in all animal cells
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What is a cytoskeletal motor protein?
One that interacts with a polarised cytoskeletal filament and moves along it using energy from ATP hydrolysis
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What 6 things do motor proteins differ in ?
filaments they bind to, direction of movement, cargo they carry, step size, duty ratio, prossecivity
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What is the duty ratio?
the % of time throughout ATP cycle a motor protein spends bound to filament
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What is processivity?
How many steps are taken before dissociation from a filament
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What does dyenin's linking to cargo via dynactin allow it to do?
Associate with end binding proteins, which associate with growing tips of MT's... can hence 'hitch a ride' on growing + end, and when stabilised then bind cargo and travel back to - end
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What is produced when you add chymotrypsin to myosin?
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What is produced when papain is then added?
S1 (head domain) and S2 (tail domain) produced
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What happens when the S1 domains are Adsorbed to glass in random orientation- add purified filaments and wash with ATP
get crawling w. - end leading (hence walking to + end), and only myosin in correct orientation moves
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What are the two proposed mechanisms of cell crawling?
(a) cell constantly being reformed at the front and degraded at the back (b) solid structure where front pushed outwards
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Describe an experiment to test this
label the front part of the structure, and if (a), then cell will move over it. If (b) it will remain in the same position within the cell
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What type of cadherin is important in embryo development? At which stage does it become important? How is this remonstrated?
E-cadherin. Past 8 cell stage when cells become densely packed. Use EDTA to remove calcium- embryos cannot progress past 8 cell stage
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Tissue organisation: Cells in ectoderm express (a). They then start to express (b), which..... Some of those cells then start to express (c), and.... As they migrate further away (d)
a) E-cadherin b) N-cadherin, want to maximise binding to each other so associate. c) cadherin-7... migrate away from neural tube as a clump. d) stop expressing cadherin altogether
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If dissociate cells from embryo, and then mix back together, what will happen. What will happen if you do this with (a) adult liver/kidney tissues (b) highly organised adult tissue
Sorting out will occur- whereby cells at early stage of differentiation organise themselves into something that resembles original tissue. (b) same thing (c) nothing
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If took fibroblasts and expressed higher levels of cadherin in some cells than others, what would happen?
Those expressing higher levels = on inside (maximises number of contacts)>
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What would happen if some cells expressed 2 types of cadherin, and others just one?
Cells expressing 2 types comprise inside layer
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What if some cells express N, and others E cadherin in equal amounts?
Separate into two separate balls
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Card 2


What i caused by deficiencies in it?


Epidermolysis bullosa, muscular dystrophy, neurodegeneration

Card 3


What family are Cdc42, Rho and Rac part of?


Preview of the front of card 3

Card 4


What role do they each play in the regulation of the cytoskeleton?


Preview of the front of card 4

Card 5


Which is the master of cell polarity?


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