Mitosis Flashcards
Alpha or Beta Tubilin is the site of growth on a microtubule
Beta
How many molecules in a ring on a microtubule
13
What is the site of initial nucleation or addition called?
Gamma Tubulin
How many centrosomes exist in a normal cell not undergoing mitosis
- during replication it is duplicated giving rise to the second one
Kinesin is a motor protein that moves toward the…
+ end of the microtubule
Dyneins is a motor proteins that moves toward the….
- end of the microtubule
Catasrophe is…
destruction from the + end towards the minus end
Rescue is
Rebuilding after catastrophe towards the + end
Loss of what energy molecule causes catastrophe
GTP
What role do MAP’s have during catasrophe
MAP’s slow catastrophe allowing GTP an opportunity to rebind to the cap and stabilize the microtubule
What is the average half life of normal microtubules in a cell (non mitotic)
15-30 minutes
How does nuclear disintegration effect MAP
Something is released upon disintegration of the nucleus that causes all of the MAP’s to fall off reducing the half life of microtubules from 15-30 minutes to 30 seconds
What are the three types of microtubules at metaphase
kinetochore MT’s (- end at centriole, + end at chromosome)
Polar MT’s (- end at centriole, + end in middle, binds to ones from the other pole)
Astral MT’s (+ end is distal, searching for missing chromosomes)
Key event in Anaphase A
chromosomes move towards the spindle poles
Key event that happens in Anaphase B
spindle poles move toward the poles of the cells
How does the polar microtubule overlap region stay in contact despite the spindle poles moving away from each other
They continue to grow at the + end
Anaphase A movement consists of what kind of movements at either end of the structure
80% of the kinetochore moving down the kinetochore microtubule and 20% of the centriole breaking apart the microtubule reeling the chromosome in
Some astral fibers reach the membrane and dynein does what
tries to move towards the - end toward the centriole ultimately pulling the centriole towards the membrane
What is the mechanism of action of Taxol and epithilones
Stabalize MT preventing catastrophe, inhibits the MT from searching and attaching to chromosomes
What is the mechanism of action for colchicine and vinlastine
cause MT to undergo catastrophe and not able to rebuild
Explain the involvement of defective MT in Alzheimer’s
abnormal MAP falls off MT and forms its own filament structure (plaque)
What are the MT stabilizing chemotherapy agents?
Taxol and Epithilones
What are the MT depolymerizing chemotherapy agents?
Colchincine and vinblastine
Phosphorylation has what effect on gamma tubulin?
Allows for it to be nucleated and grow
