lecture 13 (cytoskeleton) Flashcards
what is the main function of microtubules?
transports and positions membrane enclosed organelles to intercellular transportion
what is the subunit of one dimer in microtublues?
alpha/beta tubulin noncovalently bonded
True or False: tube structure is made of 15 parallel protofilments
False, 13
what are the organized centers that microtubles usually grow from?
1) centrosomes
2) mitotic spindle
3) basal body of cilium
4) from existing microtubules
what is the major microtubule organizing centre in Animal Cells?
centrosomes
True or False: the plus and minus end was named refering to the electrical charge of the microtubules
False, refering to the addition and subtrsction of tublin from either side
when does dynamic instability occurs?
once microtubule grows and shrink
how to prevent disassembling (depolymerization) of tubulins?
by stabilizing the plus end and attaching it to another molecules or cell structure
what will the attachement of the microtubules to a distant structure result in?
a stable link between the structure and centrosome will form
when will the microtubules grow?
when GTP tubulin is added
when will microtubules shrink?
when GDP tublin is formed
which tubulin dimer is bound to GDP?
Beta tubulin
True or False: in the growing + end beta tubulin are capped by GTP beta Tubulin
True
what causes the protofilaments to peel outwards?
having GDP tubulin at the postive end
where does the microtubule get the energy to dissasemble?
from the energy deruven from GTP hydrolysis
function of Taxol drug
binds and stabilizes microtubules allows it to grow but not shrink
function of colchicine and vinblastine:
they bind to tubulin dimers and prevent growth causing the microtubules to shrink until the spindle fiber dissappers
Taxol, vincristine, and colchicine drugs are used to treat:
cancer
what is dynamic instability?
the switching between shrinking and growing of tubulins
what does the stabilization of microtubules do?
it maintains the organization of differentiated cells
what are the two motor cell protein?
kinesins (exocytosis) & dyneins (endocytosis)
what is the similarity between kinesins and dyneins?
they both are dimers that have two ATP binding heads and single tail
what does the tail of motor protein binds to?
it binds to vesicles, organelle, cargo
True or False: different motor proteins transports different type of cargo along microtubulies
True
which area does the motor protein move towards on the microtubulies?
Kinesins -> + end
Dyneins -> - end
Main function of motor proteins:
postion organelles in the cytoplasm
True or False: Cilia and Flagella Contain Stable Microtubules Moved by
kinesins.
False, dyneins
where does microtubules of cilium grow from?
basal body
