10 - Regulation of Proliferation II

Question 1

What will p53 do if everything in cell is not okay to continue the cell cycle?

Answer 1

will induce cell cycle arrest to fix whatever needs to be fixed

Question 2

What is the status of CDKs by itself?

Answer 2

inactive , off

Question 3

What will happen to CDK when the cell begins to produce cyclins?

Answer 3

cyclin = binds to CDK &raquo_space;> conformational change = active form

Question 4

How are CDKs promiscuous?

Answer 4

can bind to different cyclins

Question 5

What are the 2 categories of cyclins?

Answer 5

S-phase (D and E cyclins) | Mitotic (A and B cyclins)

Question 6

How can a cell jump to G1 from G0?

Answer 6

Rb needs to be turned off to release E2F

Question 7

What are allosteric enzymes?

Answer 7

shape-dependent enzymes

Question 8

Where was p53 discovered?

Answer 8

virally induced cancers

Question 9

About how many cancers involve a mutation in p53?

Answer 9

50%

Question 10

How many mutations in p53 is needed for the cell to lose control?

Answer 10

one = proto-oncogene

Question 11

What do viral proteins predominantly bind to on the p53 gene?

Answer 11

DNA-binding domain

Question 12

What are the viruses preventing by binding onto the p53 binding domain?

Answer 12

prevents p53 from binding onto DNA = inhibits the DNA binding mechanism of host-cell transcription

Question 13

What is the structure of p53? How is this a problem?

Answer 13

homotetramer | if one part is mutated = it is automatically dysfunctional as they won’t be able to bind stably or at all

Question 14

What are the 3 effects of p53 on cellular response when it is working?

Answer 14

cell-cycle arrest | apoptosis | prevents angiogenesis

Question 15

What other nucleic molecule does p53 also protect?

Answer 15

mitochondrial DNA

Question 16

What is Bax?

Answer 16

induces apoptosis

Question 17

What is p21?

Answer 17

one of the inhibitors p53 turns on | arrests cell cycle, evaluates if cell can be saved, if mutations can be fixed

Question 18

If the cell cannot be saved, what does p21 do?

Answer 18

induces Bax &raquo_space;> apoptosis

Question 19

In p53+/- mutation, how is p53 still working when one copy is mutated and shouldn’t work?

Answer 19

still has one other functional copy

Question 20

What can inhibit p53? (antagonist against p53)

Answer 20

MDM2

Question 21

What is MDM2?

Answer 21

inhibits p53, regulates its activity | made with help from p53

Question 22

What is the p53-MDM2 feedback loop?

Answer 22

MDM2 binds to p53 &raquo_space;> MDM2 ubiquitinylates p53 for degradation

Question 23

How many proteins of MDM2 are needed to act on p53? Why?

Answer 23

4 since p53 is a tetramer

Question 24

What is benzopyrene and why is it important?

Answer 24

chemical in cigarettes that can react with DNA when broken down and become reactive

Question 25

Where do most mutations of proteins seem to occur?

Answer 25

DNA binding domain

Question 26

What are the 2 types of hotspots for mutations?

Answer 26

within DNA and can be tissue-specific | reasons are unknown

Question 27

What is the 4-step program to transformation?

Answer 27

eliminate Rb | disable p53 | activate telomerase | acquire growth-promoting mutation or activity