extra facts

Question 1

chromosome maturation

Answer 1

increase of gamma-tubulin complexes in centrosomes

therefore more nucleation of MTs occurs

Question 2

which motor proteins drive chromosome segregation

Answer 2

kinesin-5 and dynein

Question 3

what controls MT dynamics

Answer 3

MAPs

Question 4

what controls the actin-myosin-II contractile ring

Answer 4

RhoA - a small GTPase
gets activated at the cell cortex
promotoes actin filament production by formins and assembly of myosin-II

Question 5

WASP

Answer 5

nucleation promotion factor that activates the Arp2/3 complex

Question 6

outline processes at rear end of cell migration

Answer 6

cofilin (ABP) disassembles
G-actin monomers recycled
stress fibres

Question 7

spontaneous polarisation

Answer 7

breaking of symmetry in cells in the absence of a spatial cue

Question 8

Tau protein

Answer 8

stabilises microtubules
abundant in neurons in CNS
hyperphosphorylised in alzheimer’s disease - MTs detach and become unstable/depolymerise

Question 9

initiation of apoptosis by phosphorylation

Answer 9

when the cell is deprived of growth signals
stress activated MAP kinase - Jnk becomes activated
transcription of Bim activates intrinsic pathway

Question 10

suppression of apoptosis by phosphorylation

Answer 10

growth factor binds to cell-surface receptor
phosphorylation of apoptotic proteins (Bad)
this prevents Bad binding
inhibition of Bcl-2

Question 11

phosphorylation of cdc2 cell cycle

Answer 11

S phase
cdc2 binds to cyclin and becomes activated
Thr161 on cdc2
strong cyclin binding
dephosphorylation causes cells to exit mitosis

Question 12

protein kinase A

Answer 12

2 inhibitory subunits
2 catalytic subunits

localised to specific places
inhibitory subunits released upon activation/binding

Question 13

calmodulin

Answer 13

2 or more ca2+ bind to calmodulin causing allosteric conformational change
interacts with Ca2+/CaM kinases which can activate CREB