Tumour pathology 4+5

Question 1

Mitotic division creates…

Answer 1

2 genetically identical daughter cells

Question 2

define ‘cell cycle’

Answer 2

time interval between mitotic divisions

Question 3

mitosis

Answer 3

Mechanism of cellular replication

nuclear division plus cytokinesis

Question 4

Normal cell cycle phases

Answer 4

during interphase:-
G1, S, G2, M
G1 is the first growth stage- cell makes new proteins and copies of the organelles.
S phase is when DNA replication occurs
G2 is 2nd period of cell growth- more proteins and copies of organells in prep for mitosis.
M is mitosis and cytokinesis

Question 5

G0 phase of cell cycle

Answer 5

G1 checkpoint- cell is checked for cell size- sufficient cell mass is needed to form two daughter cells. If go ahead is not reached cell may switch to a non-dividing state called G0 phase. Can return to cycle if conditions change

Question 6

What is the ‘cell cycle’

Answer 6

Ordered series of events between mitotic divisions. Has to be highly regulated because can lead to degenerative diseases or cancer.

Question 7

A cell must progress through cycle phases…

Answer 7

in the correct sequence in order to produce viable progeny (new cells)

Question 8

Cell cycle checkpoints

Answer 8

if cell size is inadequate= G1 or G2 arrest
if nutrient supply is inadequate= G1 arrest
If DNA is not replicated= S arrest
chromosome mis-alignment= M-phase arrest

Question 9

How must DNA synthesis and mitosis occur?

Answer 9

sequentially

Question 10

External control of cell cycle

Answer 10

Hormones, growth factors, cytokines

Question 11

Intrinsic factors

Answer 11

critical checkpoints

prior to G1 checkpoint- progress through was due to external factors and after it is autonomous

Question 12

Carcinogenesis

Answer 12

the initiation of cancer formation. It is caused by mutation of genetic material that upsets the normal balance between proliferation and apoptosis

Question 13

List the major aetiologies (causing) of cancer

Answer 13

uncontrolled proliferation of cells via cell cycle dysregulation
disruption of the cyclin D-pRb-E2F pathway
disruption of the p53 pathway ( two regulatory pathways)
environmental changes (chemicals, radiation, oncogenic viruses)
inherited

Question 14

uncontrolled proliferation of cells effect

Answer 14

increased rate of cell cycle may result in tumour formation

may be benign or malignant

Question 15

what causes a cell to lose control of proliferation?

Answer 15

mutations in genes regulation cell division, apoptosis and DNA repair

Question 16

Chemical carcinogenesis

Answer 16

Chemical carcinogens or their active metabolites react with DNA forming covalently bound products (DNA adducts)
Adduct formation at particular chromosome sites causes cancer

Question 17

Radiation carcinogenesis

Answer 17

High-energy radiation is carcinogenic if received in sufficient doses
ultraviolet radiation (UV-B present in sunlight)
X-rays
Gamma radiation

Question 18

Abnormal cell cycle

Answer 18

The primary defect in cancer is –

Uncontrolled cell proliferation via cell cycle dysregulation

Question 19

Absent or inactive pRb…?

Answer 19

releases the cell cycle brake- leading to over- proliferation

Question 20

p53 protein

Answer 20

important part of G1 checkpoint
transcription factor
can stimulate DNA repair, arrest the cell cycle or trigger cell death

Question 21

important point about tumour formation is that it is

Answer 21

a multi-step process

Question 22

key event in tumour formation is?

Answer 22

uncontrolled cell proliferation via cell cycle dysregulation via loss of tumour suppressor gene function

Question 23

Carcinogenesis:- heredity?

Answer 23

inherited cancer syndromes
familial cancers
autosomal recessive syndromes of defective DNA repair

Question 24

Evidence of a tumour in malignancy means absence of what?

Answer 24

a capsule

Question 25

name 2 breast cancer tumour suppressor genes?

Answer 25

BRAC1 BRAC2