Lecture 12

Question 1

The cell cycle is driven by

Answer 1

cyclin dependen kinases (Cdks)

Question 2

Cdks _____ key proteins to control their function

Answer 2

phosphorylate

Question 3

Cohesin rings are added when _________ and hold _____ together until _______

Answer 3

DNA is replicated
sister chromatids
anaphase

Question 4

The centrosome must duplicate in what phase?

Answer 4

S phase

Question 5

The centrosome nucleates more MTs in what

Answer 5

mitosis

Question 6

Each daughter cell gets a ______after _____

Answer 6

centrosome
cytokinesis

Question 7

The spindle contains how many dif groups of microtubules?

Answer 7

3

Question 8

what three microtubules do the spindles contain?

Answer 8

astral MT
kinetochore MT
interpolar MT

Question 9

Kinetochore MTs

Answer 9

MTs have to find and attach to the kinetochores - must be able to undergo co-ordinate assembly and disassembly

Question 10

interpolar MTs

Answer 10

MTs growing from one pole must meet those from the other pole and form anti-parallel interactions

Question 11

Astral MTs

Answer 11

highly dynamic
crucial role in anaphase

Question 12

The number of microtubules nucleated by the centrosomes ______ from prophase

Answer 12

increases

Question 13

Catastrophe

Answer 13

when MTs switch from growing to shrinking

Question 14

Why do dynamics increase? (and what is the result)

Answer 14

• some MAPs are inactivated when phsphorylated by the mitotic kinase M-Cdk
• proteins that trigger microtubule catastrophe are activated in mitosis
  result: more chance of MTs growing from each centrosome contacting each other or chromosomes

Question 15

What does the activation of condensin do?

Answer 15

chromosomes condense (prophase)

Question 16

What does the activation of microtubule catastrophe proteins do?

Answer 16

microtubules more dynamic

Question 17

What does the inactivation of MAPs do?

Answer 17

microtubules more dynamic

Question 18

what does the inactivation of nuclear lamins do?

Answer 18

nuclear envelope disassembles

Question 19

What happens in prophase

Answer 19

chromosomes condense in prophase because condensins compact the DNA

Question 20

What are condensins activated by in prophase?

Answer 20

by phosphorylation by M-Cdk

Question 21

What happens when the bipolar miotic spindle starts to form?

Answer 21

MTs growing from the two centrosomes meet and start to interact via antiparallel interactions

Question 22

What does the overlap zone drive?

Answer 22

pole separation

Question 23

How does the mitotic spindle get set up?

Answer 23

the kinesin Eg5 cross-links anti-parallel microtubules and starts pushing the centrosomes apart to form the spindle pores

Question 24

the Kinesin Eg5 ______ anti-parallel microtubules and starts pushing the ________ apart to form the spindle poles

Answer 24

cross-links
centrosomes

Question 25

Eg is also needed for ____

Answer 25

anaphase

Question 26

Eg5 inhibition blocks _____

Answer 26

bipolar spindle formation

Question 27

Monopolar spindle

Answer 27

Eg5 inhibition with moastrol prevents cetrosomes from separating in prophase and prometaphase

Question 28

Anti-parallel interactions mediated by Eg5 ___ the microtubules

Answer 28

stabilize

Question 29

Prophase to pro-metaphase transition

Answer 29

the nuclear envelope disassmebles at prometaphase in many species

Question 30

When do the nuclear envelope and nuclear lamins reassemble?

Answer 30

Telophase

Question 31

What does the golgi apparatus do in pro-metaphase so that each daughter cell inherits equal amounts of golgi apparatus membranes?

Answer 31

fragments

Question 32

Secretion and endocytosis __ during the prophase to pro-metaphase transition

Answer 32

stop

Question 33

What is the result of everything that happens during the prophase to pro-metaphase transition?

Answer 33

more chance of MTs growing from each centrosome contacting chromosomes quickly

Question 34

Kinetochore

Answer 34

specialized protein structure that assembles on to the cetromere region of the chromosome in prophase

Question 35

What allows the kinetochore to move along the attached MTs?

Answer 35

Dynein and kinesin

Question 36

What is the goal of kinetochore movement?

Answer 36

for the two kinetochores on one chromosome to become attached to MTs coming from opposite poles

Question 37

Properties of kinetochore (5)

Answer 37

- specialized chromosomal structure needed for spindle attachment - binds multiple MTs at once - microtubule bundles attached to the kinetochore can switch between growing and shrinking in regulated way - kinetochores move in both directions along MT by harnessing MT assembly and diassembly and using dynein and kinesins - kinetochores properly attache to MT from both poles are under tension - tension is needed before mitosis can proceed