Cell Bio Final Ho14 Cards

Front 1

cyclin-dependent kinase complex

Back 1

2 subunits

Cyclin: is the regulatory subunit

CDK: catalytic subunit

Front 2

G1 cyclin-CDKs

Back 2

preps cells for S phase

Front 3

Anaphase Promoting Complex (APC)

Back 3

this is a ubiquitin ligase

degrades mitotic cyclin CDK

degradation is trigger for anaphase

Front 4

S phase cyclin-CDK

Back 4

activates DNA replication origins

Front 5

Cell fusion experitments showed?

Back 5

soluble diffusable factors regulate cell cycle

Mitotic cyclin-CDK complex cause

a. chromosome condensation

b. disassembly of nuclear envelop in G1 & G2 when they are fused to mitotic cells

Front 6

Plants don’t have

Back 6

centreols

Front 7

Plants don't do what?

Back 7

cytokinesis

they just build membrane/cell wall to separate daughter cells

us osmotic pressure to expand

Front 8

S. Pombe

Back 8

fission yeast

Front 9

S. Cerevisiae

Back 9

budding yeast

Front 10

cdc2

Back 10

Pombe's CDK

Front 11

cdc28

Back 11

Cerevisiae's CDK

Front 12

how many cyclins does Pombe have?

Back 12

1

Front 13

What is the name Pombe's cyclin?

Back 13

Cdc13

Front 14

How many cyclins does Cerevisiae have?

Back 14

many --> 7

Front 15

Maturation-promoting factor (MPF)

Back 15

stimulates meiotic maturation of oocytes

stimulates mitosis in somatic cells

Front 16

_____________ & _________ change together in cycling Xenopus egg extracts

Back 16

Cyclin B levels and MPF kinase activity change together in cycling Xenopus (frog) egg

--> Cyclin B activates Kinase activity of MPF

Front 17

What does APC need to be active in Late anaphase of Xenopus

Back 17

specificity factor Cdh1

this allows APC to Ub MPF for degradation

Front 18

what inactivates Cdh1?

When is this present?

Back 18

Cdc14 phosphatase removes P from Cdh1(inactive)--> inactivates APC

late anaphase

Front 19

Targets of MPF include

Back 19

condensins -->chromatin condensation

various microtubule-associated proteins involved in mitotic spindle formation

lamins (Intermediate filaments) --> degradation of the nuclear envelope

Front 20

What is cohesin?

Back 20

protein that binds sister chomatids

Front 21

What degrades cohesin --> allowing spindel apparatus to separate chromatids in annaphase?

Back 21

Separase degrades cohesins

Front 22

What inhibits Separase?

Back 22

Securin

Front 23

How is the separation of sister chromatids regulated?

Back 23

through Cdc20

Front 24

walk through how Cdc20 is the linch pin to separate sister chromatids

Back 24

Cdc20 directs APC to tag (poly Ub) securin for proteolysis -->

w/out securin Separase cleaves cohesin & sister chromatids can separate

Front 25

which is activated first: Cdc20 or Cdh1?

Back 25

Cdc20 b/c Chromatids separate (anaphase)

APC can then switch out Cdc20 for Cdh1 & degrade MPF

No/little MPF is the trigger for telophase

Front 26

what is the MPF & the cyclin that activates it in Pombe?

Back 26

MPF=cdc2 this is a Cyclin Dependent Kinase

cyclin= Cdc13

Front 27

MPF components are conserved between

Back 27

higher & lower Eukaryotes

Front 28

In Pombe, what does Cdc13 need so that it can activate MPF (Cdc2)

Back 28

Cdc needs only Threonin161 Phosphorylated

Front 29

What Phosphorylates T161 of Cdc13 in Pombe?

Back 29

CDK Activating Kinase (CAK)

Front 30

what does CAK need to phosphorylate T161 residue of Cdc13?

Back 30

CAK needs Tyrosine15 phosphorylated so it can phosphorylate T161 of Cdc13

Front 31

whats special about the Y15 residue of Cdc13

Back 31

Y15 must be P-lated by Wee1 so CAK can P-late T161

Y15 forms part of the active site of MPF --> P-lated Y15 inhibits MPF activity

Front 32

Whats good about Cdc25

Back 32

Pombe Phosphatase acts on Cdc13

Removes P from Y15 when T161 is P-lated

Front 33

Walk me through activation of MPF in pombe

Back 33

1. Cdc2 binds w/Cdc13

2. Wee1 kinase P-lates Y15 of Cdc13

3. CAK P-lates T161 of Cdc13

4. Cdc25 de-P-lates Y15 -->MPF Active!

Front 34

Pombe that are abnormally long probably have?

Back 34

defective Cdc25

too much Wee1

Front 35

Pombe that are too small probably have?

Back 35

Excess Cdc25

Defective Wee1

Front 36

Cdc13 in ______ is similar to _______ in humans

Back 36

Cdc13 in Pombe is similar to cyclin A in humans

Front 37

Cdc2 in Pombe is similar to _____ in humans

Back 37

Cdc2 in Pombe is similar to CDK2 in humans

Front 38

in S. cerevisiae what is critical for entery into S phase?

Back 38

CDK bound S phase cyclins

Front 39

how many CDK's does cerevisiae have?

Back 39

one: Cdc28

Front 40

what are the S phase cyclins in cerevisiae that are needed to start DNA synthesis?

these are early S phase cyclins

Back 40

Clb5

Clb6

Front 41

Cerevisiae: whats the checkpoint btw G1 & S phase?

Back 41

Removal of inhibitor & binding of S phase cyclins to CDK

Front 42

What is the inhibits Clb5 & Clb6 from binding Cdc28?

Back 42

Sic1

Front 43

What causes Sic1 to be tagged w/Ub & degraded?

Back 43

P-lation of Sic1 causes it to be Ubiquinated --> degraded

Front 44

Who P-lates Sic1?

Back 44

Late G1 cyclins-CDK

Front 45

Cervesia: who are these late G1 cyclins & CDK

Back 45

cerevisiae:
Late G1 cyclins= Cln1 & Cln2

CDK: Cdc28

Front 46

cerevisiae: Which cyclins are built up in late G1?

Back 46

Late G1 cyclins: Cln1 & Cln2

Early S-phase cyclins: Clb5 & Clb6

Front 47

Temp sensitive mutants were used to figure out what?

Back 47

Cln1 & Cln2 G1 cyclins of cerevisea are needed to get out of G1 & into S phase

Front 48

Walk through how the steps to get past the checkpoint btw G1 & S phase in cerevisiae

Back 48

1. Cdc28-Cln1 & Cdc28-Cln2 P-late Sic of Sic1-Cdc28-Clb5 & Sic1-Cdc28-Clb6

2. Sic1 is then tagged for Ub --> proteasomal degradation

3. Cdc28-Clb5 & Cdc28-Clb6 are active & able to P-late--> Starts synthesis