ch17

Question 1

CDKs (cyclin-dependent kinases)

Answer 1

-accelerators
-cdk level does not change

Question 2

Cyclins

Answer 2

substrate for CDK’s
-non-enzymatic
-brakes
-cdk level changes
1. bind to CDK
2. phosphorylate CDK
3. Involvement of inhibitory proteins

Question 3

positive feedback loop

Answer 3

-control when cells decide to grow to stop growing
-help cells switch between stages
-Cdc25 is stimulated by active M-Cdk

Question 4

negative feedback loop

Answer 4

-causes a system to change in the opposite direction from which it is moving
-M-Cdk sets in motion a regulatory process that leads to its own inactivation

Question 5

accelerator pedals

Answer 5

-G1-Cdk
-G1/S-Cdk
-S-Cdk
-M-Cdk

Question 6

brake pedals

Answer 6

provide information about extracellular environment, DNA damage, and spindle assembly

Question 7

G zero

Answer 7

-Terminally differentiated cells (neurons)
-Cells enter in low nutrient conditions or damaged (cell cycle arrest)

Question 8

Cell cycle arrest

Answer 8

-when DNA damage blocks cell division
-protein kinases are recruited to damage site and initiate signaling pathway
-p21 binds and inactivates G1/S-Cdk and S-Cdk complexes, arrested the cell in G1.

Question 8

Anaphase promoting complex

Answer 8

Initiates the metaphase-to-anaphase transition & assembles polyubiquitin chains on target protein

2 substrates: Mitotic cyclin & Securin

-Activated by Cdc20

Question 8

Story of M-Cdk

Answer 8

Rb and E2F check everything before division
M-CDK directs chromosomes to line up, APC gives signal to move to final division stage
p53 will send alerts if it notices danger

Question 9

Rb

Answer 9

controls when a cell grows, divides, and stops dividing

Question 9

E2F

Answer 9

activating genes necessary for cell division

Question 10

p53

Answer 10

preventing cells w/ damaged DNA from proliferating and becoming cancerous through repair or apoptosis

Question 10

Tyrosine kinase receptor

Answer 10

Mitogens stimulate G1-Cdk and G1/S-Cdk activities
Receive signal, pass it on, start cell jobs, cell cycle connection, keep balance

Question 11

Myc

Answer 11

increases the expression of many delayed-response genes

-team boss, gives instructions

Question 11

Immediate early

Answer 11

MAP kinase cascade leads to increased expression of numerous immediate early genes (including Myc)

-hear bell and get working

Question 12

delayed response

Answer 12

workers starting tasks later

Question 13

Cell cycle explained

Answer 13

Cyclins and CDKs bind together, cyclin inhibitors pause/stop to help control speed, checkpoint to make sure everything is good and if not, p53 stops and fixes problem, repeat

Question 14

Cyclin Inhibitors

Answer 14

-Inhibitory Phosphate (inhibits activation)
-P27 protein (helps control)
-p53 protein