9 - Regulation of Proliferation I

Question 1

If the cell is not the correct size, what is it missing?

Answer 1

more cytoplasm, more cell membrane, enough organelles

Question 2

Why aren’t cells such as neurons and cardiac cells ever tumors? How can this change?

Answer 2

they don’t divide | can change via viral infection

Question 3

What stages does Interphase consist of?

Answer 3

G1, S, and G2

Question 4

What does Rb do if the cell cycle is off?

Answer 4

binds to E2F = no transcription = no entry into S-phase

Question 5

What does Rb do if the cell cycle is on?

Answer 5

releases E2F = transcription = early into S phase

Question 6

What is the effect on the cell cycle if both copies of Rb are mutated? What type of gene is Rb?

Answer 6

no cell cycle arrest | tumor suppressor

Question 7

When in the cell cycle is Rb phosphorylated?

Answer 7

late G1

Question 8

What happens when Rb is phosphorylated?

Answer 8

conformational change = release E2F

Question 9

What does hypo-phosphorylation mean in terms of Rb?

Answer 9

under phosphorylated &raquo_space;> inhibiting and active Rb

Question 10

What does hyper-phosphorylation mean in terms of Rb?

Answer 10

over-phosphorylated &raquo_space;> not inhibiting = inactive Rb

Question 11

What is CDK?

Answer 11

cyclin-dependent kinase = needs cyclin

Question 12

What transcription factor helps make cyclins?

Answer 12

E2F

Question 13

In which 2 blastomas are Rb dysregulation found?

Answer 13

osteosarcoma | retinoblastoma

Question 14

What are two ways an individual can have loss-of-function mutations in tumor suppressor genes?

Answer 14

sporadic | hereditary

Question 15

What are sporadic mutations?

Answer 15

non-hereditary, picked up along the way

Question 16

What are hereditary mutations?

Answer 16

born with at least one copy mutated, can pick up second one along the way | most people with this will develop tumors

Question 17

When can second mutations occur?

Answer 17

during strand invasion (cross-overs)

Question 18

What does the Ras gene do?

Answer 18

GTP protein that activates the MAP-Kinase cascade &raquo_space;> turns on E2F

Question 19

What kind of gene is Ras?

Answer 19

proto-oncogene

Question 20

What happens if Ras was mutated?

Answer 20

cannot hydrolyze GTP into GDP = GTP stays in Ras &raquo_space;> signal stays on = constantly activates domino effect in absence of growth factor

Question 21

What amino acid change is due to the mutation in Ras?

Answer 21

Gly to Val

Question 22

What is c-myc?

Answer 22

transcription factor that can make more E2F and other cell cycle genes

Question 23

What does c-myc stand for? What turns c-myc on?

Answer 23

cellular myc gene | turned on by the Ras/MAPK cascade

Question 24

What are mitogens?

Answer 24

proteins that induces cell division

Question 25

What is c-myc called when it is hijacked by viruses?

Answer 25

v-myc (v = viral)

Question 26

What are the effects of translocating the c-myc gene?

Answer 26

can be turned on if translocated next to an active promoter

Question 27

What happens if c-myc was turned on and then turned off? And then turned on again?

Answer 27

off = cells differentiate | back on = cells die

Question 28

In which stages of the cell cycle do we have 4N chromosomes?

Answer 28

G2 and beginning of M-phase

Question 29

What happens to the genome at the end of apoptosis?

Answer 29

genome gets degraded into fragments (smaller than 2N)

Question 30

What are the 2 types of drugs (discussed in class) that can affect the cell cycle phases?

Answer 30

G2 arrest drugs | drugs that can cause cell cycle arrest and lead the cell to apoptosis

Question 31

What is PI staining used for?

Answer 31

stains DNA to observe DNA content of cells

Question 32

What does BrdU stain?

Answer 32

stains uracil

Question 33

What is the purpose of BrdU staining?

Answer 33

can indicate where the cell is in S-phase

Question 34

What is the purpose of using antibodies in BrdU staining?

Answer 34

can tell you if the cells are in M or G2 phase