lectures 13-15

Question 1

cyclin characteristics

Answer 1

-positive CDK regulator
-degraded after each cycle

Question 2

cell cycle regulation (3)

Answer 2

1. CDK/cyclin synthesis/degradation
2. CDK inhibitors
3. phosphorylation of CDK’s

Question 3

checkpoint kinases

Answer 3

-negative CDK regulators
-hold cell cycle until repair completed

Question 4

G1 function

Answer 4

growth and preparation for next mitosis

Question 5

S function

Answer 5

DNA replication

Question 6

G2 function

Answer 6

grow and prepare for mitosis

Question 7

mitosis function

Answer 7

segregate 1 copy of each chromosome to daughter cells

Question 8

model organisms cell cycle studies

Answer 8

-budding/fission yeasts (S. Cerevisiae, S. Pombe)

Question 9

observe cell cycle in fission yeast by:

Answer 9

changes in cell size

Question 10

mating pheromone arrest yeasts in:

Answer 10

late G1

Question 11

nocodazole function

Answer 11

-disrupt mitotic spindle formation
-arrest in pro-metaphase

Question 12

hydroxyurea/thymidine function

Answer 12

-inhibit dNTP synthesis
-arrest in early S phase

Question 13

flow cytometry steps (3)

Answer 13

1. ethanol - degrade DNA
2. DNA dye (propidium iodide)
3. capillary, lasers detect amount of DNA in each cell

Question 14

1C flow cytometry graph phase

Answer 14

G1

Question 15

2C flow cytometry graph phase

Answer 15

G2

Question 16

study leading to CDK discovery

Answer 16

temperature sensitive mutants in S.Cerevisiae

Question 17

enzymes used to regulate cell cycle progression (3)

Answer 17

1. cyclin-CDK protein kinases
2. protein phosphatases
3. ubiquitin-protein ligases

Question 18

S phase initiation enzyme and function

Answer 18

SCF ubiquitin-protein ligase
-ubiquitinates S phase inhibitors

Question 19

mitosis - anaphase initiating enzyme and function

Answer 19

anaphase-promoting complex (APC)
-ubiquinates inhibitors and mitotic cyclins

Question 20

CDK inhibitors (3) and removal

Answer 20

INK, CIP, KIP
-removed by phosphorylation by previous CDK-cyclin

Question 21

protein-ubiquitin ligases (2)

Answer 21

-SCF - G1->S
-APF - early M

Question 22

CDK-activating kinase function

Answer 22

-phosphorylate Thr at active site of CDK’s

Question 23

Wee1 kinase function

Answer 23

-phosphorylate Thr&Tyr on CDK
-inhibit mitotic kinase in S-phase

Question 24

Cdc25 phosphatase function

Answer 24

-remove inhibitory phosphorylation on Thr/Tyr from Wee1
-activate G1/S and mitotic CDK’s

Question 25

Cdr2 function

Answer 25

inhibit Wee1 when cell reaches size to divide

Question 26

Whi5 function

Answer 26

transcriptional repressor/suppressor

Question 27

SBF function

Answer 27

transcriptional activator

Question 28

S.Cerevisiae G1->S transition steps

Answer 28

1. Nutrients allow tln. of Cln3 mRNA, activating Cln3-CDK 2. Cln3-CDK phosphorylates Whi5, releasing Sbf 3. txn. of CLN1/CLN2

Question 29

Rb function

Answer 29

-transcriptional suppressor/repressor -mutated in cancers

Question 30

E2F function

Answer 30

-transcriptional activator

Question 31

vertebrate G1->S transition steps:

Answer 31

1. growth factors stimulate G1 CDK's 2. Cyclin-D-CDK4/6 phosphorylate Rb, releasing E2F 3. Cyclin E, CDK2 & E2F genes are transcribed

Question 32

Sic1 function

Answer 32

-S-phase inhibitor -6 phosphorylation sites

Question 33

proteolysis of S phase inhibitor steps

Answer 33

1. G1/S CDK's phosphorylate Sic1 2. SCF ubiquitinylated 3.S-phase CDK's recruit MCM helicase activators

Question 34

M exit / Early G1 proteins / pre-replication complex

Answer 34

-Cdc6 -Cdt1 -MCM helicase

Question 35

DDK function

Answer 35

-late G1 -phosphorylate MCM, activating helicase

Question 36

Sld2/Sld3 function

Answer 36

-phosphorylate Cdc6/Cdt1 to prevent reloading -phosphorylate MCM to remove

Question 37

CMG helicase complex components (3)

Answer 37

-GINS -Sid2 -Cdc45

Question 38

mediator kinases

Answer 38

ATR, ATM

Question 39

p53 function

Answer 39

-tumor suppressor TF -activate txn of p21 -arrest cell cycle, induce apoptosis

Question 40

replication stress activates ___ activating ___

Answer 40

ATR, Chk1 -inactivate Cdc25 -arrest entry to mitosis

Question 41

trophic factors function

Answer 41

suppress apoptosis

Question 42

apoptotic bodies flow cytometry graph

Answer 42

-less DNA than normal cells -before G1 phase 1C peak

Question 43

COMET assay apoptotic bodies

Answer 43

-comet-like tail

Question 44

C.Elegans number of cells

Answer 44

-959 somatic -131 apoptotic

Question 45

horvitz discovered:

Answer 45

-Lin mutants don't kill cells -CED mutants responsible for killing

Question 46

ced-3 function

Answer 46

-pro-apoptotic, necessary for apoptosis

Question 47

Bcl-2 function

Answer 47

prevent activation of Apaf-1 and suppress Cyc C release

Question 48

Bid/Bim BH-3 function

Answer 48

inhibit Bcl-2 and activate apoptosis

Question 49

cyt c function

Answer 49

activate Apaf-1

Question 50

Apaf-1 function

Answer 50

activate caspase 9 initiator

Question 51

caspase 9 function

Answer 51

proteolyse and activate caspase-3,7, initiator caspase

Question 52

caspase-3,7 function

Answer 52

proteolyse targets inducing apoptosis, effector caspases

Question 53

pro-apoptotic proteins

Answer 53

-Bak, Bac, Bax

Question 54

pro-survival proteins

Answer 54

-Bcl-2, Bcl-xl

Question 55

intrinsic death pathway steps (3)

Answer 55

1. DNA damage sends Puma 2. Puma binds Bak,Bax & Bcl-2 3. Bak/Bax form oligomeric channel to release Cyt C

Question 56

lack of adhesion apoptosis steps (3)

Answer 56

1. integrin disrupted 2. Bim released, binds Bak/Bax 3. pore formation and Cyt C release

Question 57

extrinsic death pathway steps (4)

Answer 57

1. TRADD/FADD bind death domain 2. FADD recruits and dimerizes initiator caspase-8 3. caspase-8 cleaves and activates caspases-3,6,7 4. tBid activated, binds Bcl-2 and release Cyt C