Cytoskeleton Flashcards
main function of the cytoskeleton
cell shape, cell wall formation, intracellular movement, cell metabolism
cytoskeleton is composes of what 2 parts mainly
microtubules and actin filaments
Microtubules
structure of MTs (3 main pieces)
tubulin dimers, 13 protofilaments, polarity
MTs are composed of 2 types tubulin dimers:
alpha-tubulin and beta-tubulin
Microtubules are formed by 13 protofilaments that form [blank]
a hollow tube
MTs exhibit polarity, at what end does growth occur
growth at the (+) end, it also has a (-) end
Are MTs dynamic?
Yes, constantly growing and shrinking, which makes them a bit unstable
How is the instability of MTs regulated
regulated by the GTP/GDP state of the tubulin dimers
MTs are approx how long
25nm tubes
actin filaments are approx how long
7nm, aka microfilaments
GTP bound beta tubulin’s form? straight or bent? assembly or dissasembly?
GTP bound beta tubulin is straight, assembly
GDP bound beta tubulin is straight or bent? assembly or dissasembly?
GDP beta tubulin is bent, dissasembly
MT Polymerization and Catastrophe
how does a MT grow
add GTP dimers at the (+) end
how does MT catastrohpe happen
loss of GTP cap due to hydrolysis leads to rapid breakdown
how does EBI (End Binding Protein) influence MT dynamics
- binds to (+) end to GTP cap
- stablize elongation, prevent catastrophe
- guides growth and speed