Chromosome segregation

Question 1

What can chromosome mis segregation lead to

Answer 1

Somatic cells- cancer
Gameto-genesis- downs syndrome

Question 2

What are the 2 stages of M phase

Answer 2

Nuclear division
Cytokinesis

Question 3

What are the stages in mitosis

Answer 3

Prophase, Prometaphase, Metaphase, Anaphase, Telophase, Cytokineses

Question 4

What happens in prophase

Answer 4

Chromosomes condense and centrosomes separate to form mitotic spindles

Question 5

What happens in prometaphase

Answer 5

Nuclear envelope is broken down, microtubules interact with chromosomes

Question 6

What happens in metaphase

Answer 6

Chromosomes bi-orient on the spindle and align on the metaphase plate

Question 7

What happens in anaphase

Answer 7

Sister chromatids separate and move towards the spindle poles
Spindle poles move apart

Question 8

What happens in telophase

Answer 8

Chromosomes arrive at the poles and de-condense, envolope reassembles

Question 9

What happens in cytokinesis

Answer 9

Contractile ring contracts and divided the cytoplasm

Question 10

What type of feedback does M-CDK complexes give

Answer 10

A positive feedback on its activation

Question 11

What do M-CDK’s promote

Answer 11

Spindle assembly, kinetochore assembly, chromosome condensation

Question 12

What can inactivate an M-CKD

Answer 12

An active APC/C complex (anaphase-promoting complex)

Question 13

How are sister chromatids prepared for mitosis

Answer 13

The cohesion complex establishes sister chromatid cohesion during S phase

Question 14

What do micro-tubule associate motors do

Answer 14

Transport cargo along MT’s and regulate sliding between them

Question 15

What are the two kids on MT associated motors

Answer 15

Kinesin and Dyneins

Question 16

What do kinesin-5 and -14 do

Answer 16

Bridge interpolar MT’s and regulate the length of the spindle

Question 17

what does kinesin-4,10 do

Answer 17

Push chromosome arms towards the metaphase plate

Question 18

What does dynein do

Answer 18

Pulls astral MT’s on the cell cortex to orient the spindle
Focus’s the MT’s at spindle poitn

Question 19

What tool can be used to see the molecular motors

Answer 19

Optical tweezer

Question 20

How are the MTOC’s organized

Answer 20

& copies of y-tubulin small complexes arranged in a spiral.
Nine-fold symmetry

Question 21

What does S-CDK stimulate

Answer 21

Centrosome duplication in G1/S phase

Question 22

How many MT’s attach to each chromatid

Answer 22

20-30

Question 23

What type of nucleosome is commonly found in centromeres

Answer 23

CENP-A (a centromere specific histone H3)

Question 24

What are the key molecules in kinetochore-microtubule interactions

Answer 24

Ndc80 complex
Dam1 complex

Question 25

What does active seperase do?

Answer 25

Opens the cohesion complex to allow sister chromatids to become separated in anaphase

Question 26

What happens in anaphase A

Answer 26

Shortening of kinetochore-MT due to MT flux and depolymerization at the + end

Question 27

What happens in anaphase B

Answer 27

Controsomes move away from each other due to sliding interpolar MTs and pulling of poles towards the cortex

Question 28

Where are the checkpoints located

Answer 28

G1/S
G2/M
Spindle assembly

Question 29

What does the G1/S phase checkpoint look for

Answer 29

DNA damage and cell size

Question 30

What does the G2/M phase checkpoint look for

Answer 30

DNA replication completion and DNA damage

Question 31

Spindle assembly checkpoint looks for

Answer 31

Kinetochore-MT attachment

Question 32

What are the sensors in the spindle assembly checkpoint

Answer 32

KNL1, Ndc80 complex

Question 33

What are the mediators in the spindle assembly checkpoint

Answer 33

Mad and Bub proteins (inhibit CDC20)

Question 34

What do the + and - signals in cytokinesis ensure

Answer 34

That it is perpendicular to the spindle axis