pathology 4

Question 1

describe the roles of G1, S, G2 AND M phase

Answer 1

G1 - growth phase
S- DNA synthesis & replication
G2- growth phase also prep for mitosis
M- mitosis occurs

Question 2

what external factors are involved in the cell cycle control?

Answer 2

hormones
growth factors
stroma
cytokines

Question 3

what helps control the cell cycle? give example

Answer 3

checkpoints , such as the restriction point (R) just before G1 phase

Question 4

what are the 3 phases of interphase in the cell cycle?

Answer 4

G1
S
G2(G0)

Question 5

if nutrient supply is inadequate what checkpoint does the cell cycle stop at?

Answer 5

stops at G1

Question 6

if cell size is inadequate what checkpoint does the cell cycle stop at?

Answer 6

G1 or G2

Question 7

what makes up the cell cycle checkpoints?

Answer 7

enzymes
specifically a catalytic sub-unit activated by a regulatory sub-unit

Question 8

What are the catalytic sub-units in cell cycle checkpoints?

Answer 8

cyclin dependent kinase (CDKs)

Question 9

what are the regulatory sub-units in the cell cycle checkpoints?

Answer 9

cyclins

Question 10

what is the active cell cycle complex called when referring to checkpoints/name of checkpoint when cyclin binds to CDK?

Answer 10

CDK/cyclin complex

Question 11

what two things regulate Cyclin dependent kinase activity ?

Answer 11

CDK inhibitors
production/destrcution of cyclins

Question 12

what does retinoblastoma gene code for?

Answer 12

codes for protein called pRb

Question 13

what does the protein pRb do?

Answer 13

inactivates E2F transcription factor which puts a brake in the cell cycle

Question 14

what are carcinogens?

Answer 14

nongenetic factors that can lead to cancer

Question 14

know the 3 types of environmental carcinogens

Answer 14

-chemicals
-radiation
-oncogenic viruses (hep 4,herpes)

Question 15

what do you call a section of DNA attached to a chemical carcinogen?

Answer 15

DNA adduct

Question 16

radiation carcinogens damages which part of the DNA?

Answer 16

targets purines & pyrimindine bases

Question 17

how does mutated retinoblastoma gene cause cancer?

Answer 17

overactive E2F transcription factor

Question 18

Dysregulation at which checkpoint causes most Cancers?

Answer 18

G1- S checkpoints

Question 19

what is the role of p53

Answer 19

maintain genomic integrity

Question 20

how does p53 work

Answer 20

p53 builds up in damaged cells
-cell cycle will arrest at G1 to help with DNA repair
-severe cases p53 induces apoptosis

Question 21

what happens if p53 is mutated?

Answer 21

there is no G1 arrest or DNA repair
causes neoplasm to occur as damaged cells proliferate to form those

Question 22

how many autosomal and sex determining chromosomes is in the human genome?

Answer 22

22 autosomal pairs

1 sex determing pair

Question 23

what are the 3 stages of the cell cycle?

Answer 23

interphase, mitosis, cytokinesis

Question 24

what are the 2 key regulatory molecules that determine progression through the cell cycle?

Answer 24

cyclin-dependant kinases (CDKs) cyclin

Question 25

what are the 2 families of CDK inhibitors?

Answer 25

INK4a(p14 and p16) CIP/KIP(p21,p21 and p57)

Question 26

what is the role of p14 in the cell cycle?

Answer 26

prevents p54 degradation

Question 27

role of p16/INK4a?

Answer 27

binds to CDK4 which arrests the cell cycle at G1

Question 28

what is p21 activated by?

Answer 28

p53

Question 29

what state is pRb when active?

Answer 29

hypophosphorylated

Question 30

what are the 3 genes that p53 can activate?

Answer 30

p21 (CDK inhibitor, G1 arrest) GADD45(DNA REPAIR) BAXX (apoptosis)

Question 31

what do genotoxins cause?

Answer 31

irreversible genetic damage by binding to DNA

Question 32

what are tumour suppressor genes?

Answer 32

genes that protect a cell from forming cancers

Question 33

what causes chemical carcinogens to occur?

Answer 33

oxidation of purines and pyrimidines in DNA

Question 34

what causes radiation carcinogenesis to occur?

Answer 34

UVB light causes thymine pairs to bond together into thymine dimers