Kinases 1

Question 1

G1

Answer 1

commitment to cell division

Question 2

S phase

Answer 2

DNA synthesis replicate genome

Question 3

G2

Answer 3

cell mass doubled

Question 4

M phase

Answer 4

cell division - mitosis and cytokinesis

Question 5

CDKs are only activated when

Answer 5

bound to cyclins

Question 6

does the concentration of cyclins or CDKs oscillate during the cell cycle

Answer 6

the conc. of CDKs stays the same

the conc. of cyclins oscilates

Question 7

APC/C

Answer 7

member of the ubiquitin ligase family - proteolytic destruction
ubiquitabtion of securing and S+M cyclins
Anaphase promoting complex

Question 8

Paul Nurse and Tim Hunt

Answer 8

PN - fission yeast - CDKs

TH - discovered cyclins in sea urchins

Question 9

WEE1

Answer 9

Kinase which is a negative regulator of cell division

Question 10

Kinase

Answer 10

an enzyme which catalyses the addition of phosphate onto substrate

Question 11

Phosphotase

Answer 11

dephosphorylates

Question 12

CDC25

Answer 12

positive cell division regulator

Question 13

when wee1 phosphorylates CDK 1 what happens

Answer 13

CDK 1 remains inactive

Question 14

when cyclin B is bound to CDK 1 and cdc25 is present

Answer 14

cdc25 dephosphorylates the complex making it active and so the cell cycle progresses from G2 –> M

Question 15

in s.pombe cdc2 is a

Answer 15

CDK1

Question 16

in s.pombe cdc13 is a

Answer 16

cyclin B

Question 17

Cdc2 is important as

Answer 17

it is a CDK 1 which causes cross from G2 to m

- mitotic spindle formation, cytoskeleton disassembly, Golgi and Er fragmenting, nuclear envelope breaks down

Question 18

Cdc2 is important as

Answer 18

it is a CDK 1 which causes cross from G2 to m

- mitotic spindle formation, cytoskeleton disassembly, Golgi and Er fragmenting, nuclear envelope breaks down

Question 19

3 major cell cycle checkpoints

Answer 19

Late G1 - is environment favourable - commit to cell cycle
G2/M checkpoint - Is all DNA replicated? is env favourable? Control system triggers early mitotic events to chromosome alignment in spindle in metaphase
Metaphase anaphase transition - are all chromosomes attached to the spindle

Question 20

cyclins each cell cycle

Answer 20

undergo cycle of synthesis and degredation

Question 21

4 classes of cyclins

Answer 21

G1/S cyclins, start, S (chromosome duplication), m Cyclins (stimulate entry into mitosis)

Question 22

full activation of the CDK-cyclin complex occurs when

Answer 22

CDK activating kinase (CAK) phosphorylates an amino acid near the entrance to CDK active site - conformational change - allowing the CDK to phosphorylate its target properly

Question 23

CDIs (CDK inhibitory proteins)

Answer 23

regulate cyclin-CDK complex by rearranging the active site and inactivating the CDK

primarily control G1/S and S-CDKs

Question 24

anaphase metaphase transition

Answer 24

APC/C - mem. ubiquitin ligase family

catalyses the destruction of securing and SandM cyclins

Question 25

securin

Answer 25

normally protects the protein linkages that hold sister chromatids together in early mitosis - destruction to progress to anaphase

Question 26

SCF

Answer 26

another ubiquitin ligase

• ubiquilate CDI proteins in late G1, and helps control S-CDK activation
• activity is constant through the cell cycle - controlled by phosphorylation

Question 27

origin replication complex

Answer 27

late mitosis and early G1

cdc6 and cdt1 bind at ORC and help to load mcm proteins

thought to serve as helices unwinding DNA

Question 28

Late mitosis early G1 app/c

Answer 28

triggers the destruction of gemini

Question 29

late G1 - APC/C turned off

Answer 29

gemini accumulates and inhibits Cdt1 formation during S phase onwards

Question 30

mitosis APC/C complex

Answer 30

triggers the destruction of securin - liberates the protease that cleaves cohesis - initiates the separation of the sister chromatids

Question 31

M-CDK

Answer 31

drives early mitosis, assembly of the spindle and ensures that the chromatids are attached to opposite poles of the spindle

also triggers the break down of the nuclear envelope, actin cytoskeleton rearrangement

Question 32

M-CDK activation - accumulation of M cyclin

Answer 32

Wee1 phosphorylates (at 2 neighbouring sites) and holds the complex in an active state until CDC25 comes along and removes the inhibition by being a phosphatase

Question 33

Mdck positive feedback loop

Answer 33

activation MCDK inhibits Wee1

Question 34

kinetochore microtubules attach

Answer 34

the plus ends of their microtubules at the kinetochore on centimetre of chromatids

Question 35

astral microtubules

Answer 35

help to position the spindle

Question 36

pericentriolar matrix

Answer 36

nucleates an array of microtubules - fast growing plus end outwards

Question 37

centrism duplication

Answer 37

same time as the cell enters S phase -G1/D-CDK (cyclin E and CDK2) trigger cell cycle entry

Question 38

M-CDk also changes the microtubule behaviour by phosphorylating 2 proteins that control

Answer 38

MT dynamics

MAPS and MT dependent motor proteins

Question 39

assembly of the contractile ring depends on

Answer 39

protein proteins - nucleate and assemble parallel array or linear unbranched actin filaments

Question 40

overlapping of actin and myosin II filaments

Answer 40

generates the force which divides the cytoplasm into 2

Question 41

which GTPase controls the assembly of the contractile ring

Answer 41

RhoA - small GTPase of the Ras superfamily