L25 - Mitosis and mitoric checkpoints

Question 1

what are CDKs

Answer 1

cyclin depednant kinases

= serine/threonine ki ases that control progression of cells through the cell cycle

Question 2

describe howWee1 and cdc25 ineteract

Answer 2

Wee1 adds inhibitor phosphatases –> inactivce even if bound to cyclin

Cdc25 –> removes inhibitory phosphatatses = active CDKs

Question 3

name a CDKI - CDK inhibitor

Answer 3

p21 = produced by p53

Question 4

describe how cyclins are degraded

Answer 4

ubiquitin mediated proteolysis

= Anaphase-promoting complex (APC) adds ubiquitin (E3 ligase(

cyclin B targtted for degredation –> allpws mitottic exit bt inactivating CDK1

Question 5

2 main functions of APC

Answer 5

APC is a E3 ubiquitin ligase that marks for destruction by 26S proteasome

degrade securin –> release seperase = cleave cohesin holding chromatids

degrade cyclin B –> inactivate CDK1

Question 6

whatdescribe the ‘wait anaphase’ signal - spindle assembly checkpoint

Answer 6

unattached kinetochores produce inhibitory signal to APC-cdc20

corrcet attachemt –> SAC silenced –> cdc20 released –> APC active