lecture 13 (cytoskeleton)

Question 1

what is the main function of microtubules?

Answer 1

transports and positions membrane enclosed organelles to intercellular transportion

Question 2

what is the subunit of one dimer in microtublues?

Answer 2

alpha/beta tubulin noncovalently bonded

Question 3

True or False: tube structure is made of 15 parallel protofilments

Answer 3

False, 13

Question 4

what are the organized centers that microtubles usually grow from?

Answer 4

1) centrosomes
2) mitotic spindle
3) basal body of cilium
4) from existing microtubules

Question 5

what is the major microtubule organizing centre in Animal Cells?

Answer 5

centrosomes

Question 6

True or False: the plus and minus end was named refering to the electrical charge of the microtubules

Answer 6

False, refering to the addition and subtrsction of tublin from either side

Question 7

when does dynamic instability occurs?

Answer 7

once microtubule grows and shrink

Question 8

how to prevent disassembling (depolymerization) of tubulins?

Answer 8

by stabilizing the plus end and attaching it to another molecules or cell structure

Question 8

what will the attachement of the microtubules to a distant structure result in?

Answer 8

a stable link between the structure and centrosome will form

Question 9

when will the microtubules grow?

Answer 9

when GTP tubulin is added

Question 10

when will microtubules shrink?

Answer 10

when GDP tublin is formed

Question 11

which tubulin dimer is bound to GDP?

Answer 11

Beta tubulin

Question 12

True or False: in the growing + end beta tubulin are capped by GTP beta Tubulin

Answer 12

True

Question 13

what causes the protofilaments to peel outwards?

Answer 13

having GDP tubulin at the postive end

Question 14

where does the microtubule get the energy to dissasemble?

Answer 14

from the energy deruven from GTP hydrolysis

Question 15

function of Taxol drug

Answer 15

binds and stabilizes microtubules allows it to grow but not shrink

Question 16

function of colchicine and vinblastine:

Answer 16

they bind to tubulin dimers and prevent growth causing the microtubules to shrink until the spindle fiber dissappers

Question 17

Taxol, vincristine, and colchicine drugs are used to treat:

Answer 17

cancer

Question 18

what is dynamic instability?

Answer 18

the switching between shrinking and growing of tubulins

Question 19

what does the stabilization of microtubules do?

Answer 19

it maintains the organization of differentiated cells

Question 20

what are the two motor cell protein?

Answer 20

kinesins (exocytosis) & dyneins (endocytosis)

Question 21

what is the similarity between kinesins and dyneins?

Answer 21

they both are dimers that have two ATP binding heads and single tail

Question 22

what does the tail of motor protein binds to?

Answer 22

it binds to vesicles, organelle, cargo

Question 23

True or False: different motor proteins transports different type of cargo along microtubulies

Answer 23

True

Question 24

which area does the motor protein move towards on the microtubulies?

Answer 24

Kinesins -> + end
Dyneins -> - end

Question 25

Main function of motor proteins:

Answer 25

postion organelles in the cytoplasm

Question 26

True or False: Cilia and Flagella Contain Stable Microtubules Moved by
kinesins.

Answer 26

False, dyneins

Question 27

where does microtubules of cilium grow from?

Answer 27

basal body