Disorders of cell growth

Question 1

cell cycle phases

Answer 1

Interphase G1G2G3, Mitosis, Cytokinesis

Question 2

cell cycle control measures

Answer 2

phases must be in correct sequence, DNA synthesis and mitosis must occur correctly, daughter cell must receive full chromosome complement, mutations must not pass on

Question 3

checkpoints of cell cycle

Answer 3

G1/ S restriction point and G2/M checkpoint

Question 4

what is checked at G1 point

Answer 4

nutrient supply, external stimulus (hormones, growth factors, cytokines), cell size, DNA damage

Question 5

what is checked at G2 point

Answer 5

cell size, DNA damage

Question 6

what is checked at S phase point

Answer 6

DNA replication

Question 7

What is checked at M phase point

Answer 7

chromosome alignment

Question 8

cell cycle dependent enzyme

Answer 8

CDKs - needs cyclin to be active. when active they phosphorylate the target proteins and orchestrate entry into next phase

Question 9

cell cycle inhibitors

Answer 9

CIP/KIP family `(p21,p27), INK4a family (p16)

Question 10

retinoblastoma protein

Answer 10

when hypophosphorylated state, the pRB is active and suppresses tumours. mutations in Rb favour proliferation

Question 11

carcinogenesis

Answer 11

failure of cell cycle control- mutations in genes regulating cell division, apoptosis, DNA repair cause loss of control of proliferation

Question 12

two frequently disrupted pathways

Answer 12

cyclin D-pRB-E2F pathway, p53 pathway

Question 13

p53

Answer 13

promotes gene repair at G1 or apoptosis if the gene repair fails. if p53 mutated then genetically damaged cells proliferate

Question 14

cyclin D-pRB-E2F pathway

Answer 14

pathway controls the G1/S transition of the cell cycle by positive and negative regulation of E2F-responsive genes required for DNA replication.

Question 15

carcinogenesis is caused by

Answer 15

oncogenic viruses, inherited factors (5-10%), genotoxins- cause irreversible genetic damage or mutations through chemicals or radiation

Question 16

why does inherited retinoblastoma not always show up in individuals with the inherited gene

Answer 16

multiple hits to DNA are necessary to cause cancer. need more than one hit for the tumour to develop

Question 17

anti-oncogenes

Answer 17

tumor suppressor genes that function to retrain inappropriate cell growth and also stimulate cell death- p16, cyclin D, CDK4, Rb

Question 18

most common types of cancer that can be genetically transmitted

Answer 18

breast, colorectal, gynaecologic, endocrine

Question 19

porto-oncogenes

Answer 19

normal genes coding for normal growth regulating proteins

Question 20

oncogenes

Answer 20

cancer causing genes- activated by alteration of photo-oncogene structure or dysregulation of expression

Question 21

process of chemical carcinogenesis

Answer 21

DNA bases react with chemical carcinogens and form covalently bound products called DNA adducts. this can lead to activation of oncogenes and loss of anti oncogenes

Question 22

how does radiation affect cells

Answer 22

target DNA bases and damage them

Question 23

how do oncoviruses work

Answer 23

virus genome inserts near a host protooncogene which causes over expression of protooncogene or virus directly inserts into and oncogene causing cell division

Question 24

types of virus that cause cancer

Answer 24

HPV (genital, throat, anal), hep B(liver) , EBV (lymphoma)