Genetics Cancer

Question 1

3 factors that cause cancer?

Answer 1

Environment- chemicals and radiation
Exogenous- viruses
Genetics- both rare and common

Question 2

7 characteristics that differentiate a cancer cell from a normal cell?

Answer 2

Large number of dividing cells
Large, variably shaped nuclei
Large nucleus to cytoplasm ratio
Variation in size and shape
Loss of normal cell features
DIsorganised arrangement
Poorly defined tumor boundary

Question 3

4 different types of cancer?

Answer 3

Carcinoma
Sarcoma-bone, muscle and connective tissue
Lymphoma
Leukaemia

Question 4

6 hallmarks of cancer?

Answer 4

Self sufficiency in growth signals
Insensitivity to anti-growth signals
Tissue invasion and metastasis
Limitless replicative potential
Sustained angiogenesis
Evading apoptosis

Question 5

What do positional cloning linkage studies do?

Answer 5

Identify cancer germline mutations

Question 6

5 types of mutations?

Answer 6

Deletions
Duplications
Inversions
Translocations
Single base substitutions (point mutations- silent, nonsense and missense)

Question 7

2 types of genetic mutations?

Answer 7

Chromosome instability

Aneuploidy

Question 8

Distinct somatic mutation in melanomas?

Answer 8

UV radiation leads to the formation of covalent bonds between two adjacent pyrimidines (C and T) in the DNA molecule

Question 9

Passenger vs driver mutations?

Answer 9

Tolerated and have no effect on fitness of clone vs mutations that confer a selective advantage and tend to drive clonal expansion

Question 10

Oncogenes?

Answer 10

Lead to accelerated cell division, need one mutation only and are gain of function

Question 11

3 ways of activating oncogenes?

Answer 11

Chromosome rearrangement, e.g formation of BCR-ABL gene on Philadelphia chromosome leads to CML
Gene amplification, e.g Myc
Mutation- e.g RAS protein no longer inactivated by GAP

Question 12

Example of rare inherited mutation?

Answer 12

Mutation in RET gene leads to MEN2

Question 13

Tumour suppressor genes?

Answer 13

Act as breaks to excessive proliferation, two mutations required and loss of function

Question 14

3 effects of p53 mutations?

Answer 14

Cells can’t stop the cell cycle to allow for DNA repair
Cell can’t carry out efficient DNA repair
Cells can’t undergo apoptosis

Question 15

How are BRCA1 and 2 involved in DNA repair?

Answer 15

BRCA1 is phosphorylated by ATM and CHK2 in response to double-stranded DNA breaks. BRCA1 then binds to BRCA2 which interacts with RAD51 to form a complex for DNA repair