week 5 reading

Question 1

filaments: NTP binding

Answer 1

actin: ATP
MTs: GTP

Question 2

actin subunit and filament

Answer 2

subunit: globular actin
filament: actin

Question 3

actin: ADP gradient

Answer 3

decreases from negative to positive end

Question 4

nucleation of actin

Answer 4

g-actin group together (spontaneously or via nucleating factors)

Question 5

Arp2/3

Answer 5

• recruits 2 filaments
• can bind on the side of the filament
• positive ends grow out

Question 6

treadmilling

Answer 6

can occur when actin isn’t permanently anchored
- length doesn’t change because segments leave at same rate as segments are added

Question 7

actin motor protein

Answer 7

myosin: head group binds and hydrolyzes ATP
- can go to + or - end

Question 8

microtubules: monomer and filament

Answer 8

monomer: aB tubulin
filament: microtubule

Question 9

microtubules: nucleation

Answer 9

gamma-tubulin ring complex: hollow straw made of 13 filaments
- anchor at negative end

Question 10

dynamic instability

Answer 10

rapid shrinking (catastrophe) or growth (rescue)

Question 11

microtubules: motor proteins

Answer 11

kinesin: go to + end
dynein: go to - end

Question 12

thymosin

Answer 12

sequesters g-actin, prevents + end interaction