Ch 17: Cell Cycle 1

Front 1

Cell cycle

Back 1

Series of steps that lead to cell division

Front 2

Function of cell cycle

Back 2

- Accurately duplicate DNA of chromosome

- Precisely segregate sister chromatids into two daughter cells

Front 3

Accurately duplicate DNA of chromosome

Back 3

Function of cell cycle (1)

Front 4

Precisely segregate sister chromatids into two daughter cells

Back 4

Function of cell cycle (2)

Front 5

Cell cycle control system

Back 5

- Comprised of regulatory proteins

- Govern progression through cell cycle

*(checkpoints)

Front 6

Checkpoints

Back 6

*cell cycle control system

- govern progression through cell cycle

- comprised of regulatory proteins

Front 7

Mechanics of cell division

Back 7

- Mitosis

- Cytokinesis

Front 8

Mitosis

Back 8

*Phase of cell division (mechanics)

- separation of sister chromatids

Front 9

Mitotic spindle

Back 9

*part of mitosis

- Made of

--Microtubules (MTs)

--MT associated proteins (MAPs)

-- MT dependent motor proteins (kinesin-related proteins/dyneins)

Front 10

MT dependent motor proteins

Back 10

*make up part of mitotic spindle

- Kinesin related proteins

- Dyneins

Front 11

Cytokinesis

Back 11

*Phase of cell division (mechanics)

- division of cytoplasm

Front 12

Contracting ring

Back 12

*part of cytokinesis

- made of...

--Actin

--Myosin

Front 13

Actin/myosin

Back 13

Make up contracting ring of cytokinesis

Front 14

Cell cycle control proteins

Back 14

- Cyclin dependent kinases (Cdks)

- Cyclins

Front 15

Cyclin dependent kinases (Cdks)

Back 15

*cell cycle control protein

- Protein kinase--> control major cell cycle events

(replication, mitosis)

- Activity rises and falls during cell cycle

Front 16

Cyclins

Back 16

*cell cycle control protein

- Major regulator of Cdk activity

- binds Cdk directly

- Changes in level controls cdk activity

- different types in different phases of cell division

(ex. M-cyclin, Cyclin B)

Front 17

M-Cdk

Back 17

Cyclin-Cdk complex

- M-cyclin+Cdk1

Front 18

Cdk activity regulation methods

Back 18

*Regulation

- Phosphorylation

- Binding of cdk inhibitors

- Proteolysis of cyclins

Front 19

Cdk activity regulated by phosphorylation

Back 19

*cdk activity regulation

- Phosphorylation of T161/Y15 site

- important in control of M-cdk activity

--uses wee1, CAK, and cdc25

Front 20

Cdk activating kinase (CAK)

Back 20

*regulates cdk activity

- phosphorylates the top of Cdk protein (T161)

- makes M-Cdk active

Front 21

Wee1

Back 21

*regulates cdk activity

- Cdk inactivating kinase

- phosphorylates bottom of Cdk protein (Y15)

- makes M-Cdk inactive

Front 22

Cdc25

Back 22

*regulates cdk activity

- Protein phosphatase

- Dephosphorylates Y15

- Makes M-Cdk active

Front 23

Active M-cdk

Back 23

- promotes entry into mitosis

Front 24

Inactive M-cdk

Back 24

- inhibits mitosis entry

- promotes exit

Front 25

Cdk activity regulated by binding of cdk inhibitors

Back 25

*cdk activity regulation

- binds inhibitor on cdk+cyclin complex (m-cdk)

- makes m-cdk inactive

- important in control of G1-S phase

-- uses CKI

Front 26

Cdk inhibitor protein (CKI)

Back 26

*regulates cdk activity

- binds to M-cdk complex on top --> inactivates

- inhibits mitosis entry

Ex: p21, p29

Front 27

CKI types

Back 27

*regulates cdk activity

- P21

- P29

Front 28

Cdk activity controlled by regulated proteolysis of cyclins

Back 28

*cdk activity regulation

- Breakdown of cyclins with proteasomes

- Inactivates cdk

-- uses ubiquitin ligase

Front 29

Proteasomes

Back 29

- Degrades cyclins tagged by polyUbiq. chain

Front 30

Ubiquitin ligase

Back 30

*regulates/controls cdk activity

- recruits ubiquitin

- forms ubiquitin chain

- degrades cylins

--Ex: SCF, Anaphase promoting complex (APC)

Front 31

Ubiquitin

Back 31

*regulates/controls cdk activity

- recruited by ubiquitin ligase

- attaches to cyclin protein and forms polyubiquitin chain

Front 32

Polyubiquitin chain

Back 32

*regulates/controls cdk activity

- acts as tag for degradation by ubiquitin ligase

Front 33

Examples of proteasomes

Back 33

- SCF

- Anaphase promoting complex (APC)

Front 34

SCF

Back 34

*regulates cdk activity

- type of ubiquitin ligase

- degrades CKI

-- activates G1/S-cdk

Front 35

Anaphase promoting complex (APC)

Back 35

*regulates cdk activity

- type of ubiquitin ligase

- degrades M-cyclin and Securtin

Front 36

Activation of M-cdks

Back 36

- triggers entry into mitosis

Front 37

M-cyclin (Cyclin B)

Back 37

Activation of M-cdk begins with accumulation of...

Front 38

Cyclin B

Back 38

*M-cyclin

- activates M-cdk when accumulated

- levels oscillate during cell cycle

Front 39

Interphase

Back 39

*M-cdk activation

- Cell cycle that increases Cyclin B synthesis

- G1--> M-phase

-- triggers entry into mitosis

Front 40

Anaphase

Back 40

*M-cdk activation

- Cell cycle that degrades Cyclin B

- Cdk1 inactivation

-- triggers exit from mitosis

Front 41

Positive feedback

Back 41

*M-cdk activation

- Abrupt increase in Cdk/cyclin B activity

- Late in G2 phase

(Cyclin B level/Cdk1 activity relationship)

Front 42

Cdk1/cyclin (M-cdk)

Back 42

*M-cdk activation

- Activates Cdc25

- Inhibits Wee1

Front 43

Activation of Cdk1/cyclin

Back 43

*M-cdk activation

- irreversible and complete

- promoted by feedback loops

Front 44

Regulation by Cdk1/cyclin B (M-cdk)

Back 44

*regulation

- Assembly of mitotic spindle (motor proteins)

- MT dynamics (MAPs) (MT binding protein)

- Chromosome condensation (condensin)

- Nuclear envelope breakdown (nuclear lamins)