Spatial control of Cell Division

Question 1

Function of Mps1

Answer 1

Localises the kinetocore

Recruits other proteins and assembles them into an inhibitory complex (MCC)

Question 2

Components of the mitotic checkpoint

Answer 2

Mps1 kinase
Kinetochore
Mitotic checkpoint complex (MCC)
Anaphase promoting complex

Question 3

Mitotic checkpoint complex (MCC) function

Answer 3

Inhibits a large ubiquitin ligase needed for mitotic exit

Question 4

When does the mitotic checkpoint end?

Answer 4

When microtubules attach

Question 5

What happens during the mitotic checkpoint

Answer 5

1) MPS1 is removed from kinetochores
2) Phosphatases are activated to dephosphorylate key checkpoint proteins
3) Microtubule motors strip the checkpoint proteins from the kinetochore down microtubules towards spindle pores

Question 6

what does MPS1 bind to?

Answer 6

NDC80

Question 7

What is NDC80 function?

Answer 7

Complex which binds microtubules at the kinetochore

Question 8

How is SAC silencing caused?

Answer 8

Competition of Mps1 and microtubules for NDC80 as they bind at the same binding site

Question 9

What is involved in error connection?

Answer 9

Aurora B
Centromere
Destabilisation of incorrect microtubule attachments

Question 10

What does Aurora B do?

Answer 10

Localises to the centromere in the kinetochore
Phosphorylates the kinetochore to remove microtubules through the electrostastic charge
Kinetochores under tension are removed away from Aurora B activity and therefore stabilised

Question 11

What is used to measure kinase activity?

Answer 11

FRET reporters

Question 12

How does FRET analysis work?

Answer 12

FRET connected to the substrate motif of the kinase, it is phosphorylated and then the phosphorylation will allow it to bind to the phosphopeptide binding domain

Question 13

What are the 5 different types of ways errors can occur in mitosis?

Answer 13

Weakened checkpoint 
Error correction defects 
Multipolar spindles 
Cohension defects 
Cytokinesis failure

Question 14

What is a weakened checkpoint?

Answer 14

One chromosome is not divided

Question 15

What is a error correction defect?

Answer 15

‘tug of war’ - one of the chromosomes is divided but is attached by both spindles

Question 16

What is multipolar defects?

Answer 16

Where there is more than two spindles

Question 17

What are cohesion defects?

Answer 17

The chromosomes is held together so you gen an uneven distribution