CBG Lecture 37:Cytoskeleton Flashcards Preview

HELENP CBG: Cell Architecture, Communication and Regulation > CBG Lecture 37:Cytoskeleton > Flashcards

Flashcards in CBG Lecture 37:Cytoskeleton Deck (70)
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1

what are the main roles of the CSK in eukaryotes

support of cell shape: microvilli, cell cortex
intracellular traffic - guides moving vesicles
cell division - mitotic spindle
motion - cell migratoin, muscle contraction

2

within a cell, where is microtubules/actin

microtubles arranged from centre outwords
actin generally on periphary/circumference

3

how does CSK help in support

microvilli
cell cortex

4

how does CSK help in intracellular traffic

guides moving vesicles

5

how does CSK help in cell division

separation of spindle poles

6

how does CSK help in motion

filapodia
flagella

7

what is CSK essential for

wound healing
sperm-egg fusion
muscle function

8

what are the 3 distinct subregions of CSK

1. microtubules:detemine organell position
2.intermediate filaments:give mechanical strength
3.microfilaments - actin filaments: give cell surface shape

9

what is a microfilament, and its role

actin
gives cell surface shape

10

what do intermediate filaments do

give mechanical strength

11

what do microtubules do

determine organelle position

12

what do motor proteins do

move organelles along the filaments of move the filaments themselves

13

what do all 3 filaments (microfilaments,intermediate filaments, microtubules) have in common

all form as helical assemblies of subunits that self-associate using a ocmbo of end to end and side to side protein contacts

14

discuss structure of intermediate filaments

rope like and hard to break but easy to bend

15

give structure of microtubules

strong rigid hollow tubes

16

give structure of microfilaments (actin filaments)

thinnest of the 3, hard to stretch but easy to break

17

whatis base unit of mictrotubules

alpha/beta tubulin heterodimer
hollow cylindrical polymer
polar filament
stiff/rigfid
GTP hydrolysis has major effect on microtubule dynamics

18

what is outer diameter of microtubules

25nm

19

what do microtubules typically have one end attacxhed to

a single MTOC (micrtubule organising centre) called a centrosome

20

talk about microtubule dynamics

beta tubulin binds GTP during polymerization, this molecule hydrolysed to GDP
GDPbound form of tubulin is unstable in the microtubule and causes microtubules to shrink between shrinking (catastrophe) and growing (rescue) phases
alpha tubulin is ALWAYS in its GTP-bound state and has a structural role
GTP hydrolysis puts the lattice under stress
when cap is lost microtubule depolmerises and peels apart

21

discuss microtubule organisation

centrosomes are MTOCs - microtubule organisation centres
gamma tubulin ring complex (gamma-TURC) within MTOC nucleates microtubule assembly
grow from + end
centrosome (interphase) spindle poles (mitosis) are MTOCs

22

what does gamma TURC do

within MTOC and nucleates microtubule assembly

23

name an MTOC in mitosis

spindle poles

24

name an MTOC in interphase

centrosome

25

how can microtubules be used to treat disease

controlling microtubule dynamics can treat gout
colchicine - affects tubulin dynamics by inhibiting polymerization and therefore relieves gout joint pain

26

name drugs that prevent polymerization of tubulin

Colchicine was first known drug
Taxol is moder drug that inhibits mitosis and used to treat some breast/ovarian cancers

27

what is movement along mictubules (MT) based on

the action of motor proteins that utilize energy derived from ATP hydrolysis to produce force and movement
such proteins: kinesin, dynein

28

what do kinesin and dynein do

move cargo along microtubule tracks

29

what are kinesins

transport cargo towards + end MT via a processive movement - lots of contact, never dissociates from MT
eg. carries NTs from Golgi to terminal branches of aoxn, generally carries AWAY from centre

30

discuss structure of kinesins

2 heavy chains wound round eachother in coiled coil and two light chains
the globular head domains of the heavy chains bind MTs and are the motor domains of the molecule