Cancer genes

Question 1

Describe DNA damage repair genes

Answer 1

Repair mechanism fro DNA (point mutations etc.)
Both (pair) fail for cancer to arise
Speeds accumulation of mutations in other critical genes

Question 2

Describe tumour suppressor genes

Answer 2

Inhibit cell cycle or promote apoptosis (self destruct)
Like breaks - both fail for cancer (one autosomal dominant/ environmental)
1st mutation - susceptible to cancer
2nd mutation - leads to cancer

Question 3

Describe the importance of BRAC1

Answer 3

Check point mediator
DNA damage signalling + repair
Chromatin remodelling (inactive X)

Question 4

Describe BRAC2

Answer 4

DNA repair by homologous recombination

Breast and ovarian cancer 50 - 85%

Question 5

Describe the function MMR

Answer 5

Corrects errors that spontaneously occur during DNA replication (insertion/deletion)

Question 6

Describe Microsatellite instability (MSI)

Answer 6

Phenotypic evidence that MMR isn’t functioning properly

Abnormal MMRs accumulates errors, increasing the chances of cancer

Question 7

What properties doc cancer cells have?

Answer 7

Loss of tumour suppressor genes
Gain of function of oncogenes
Abnormal shape/size
Capable of independent growth

Question 8

What facilitates the movement of a tumour

Answer 8

The loss of cell-to-cell adhesion

Question 9

What are the main mutations in cancer

Answer 9

Mutations at G1 and S by;

Rb, CDK4, cyclin D, p16

Question 10

What active enzyme complex is the main checkpoint in cancer

Answer 10

CDK/ cyclin complex

Question 11

What is a cyclin

Answer 11

regulatory subunit

Question 12

What are cyclin- dependent kinases

Answer 12

catalytic subunit

continuously expressed in inactive form - activated by cyclins

Question 13

What does the CDK/cyclin complex do?

Answer 13

phosphorylate target proteins which activate the substrate to regulate the next phase

Question 14

What does p53 maintain?

Answer 14

genomic integrity

Question 15

What does p53 do in damaged cells?

Answer 15

Induces cell cycle arrest at G1

Facilitates DNA repair

Question 16

Describe p53 induced apoptosis in damaged cells

Answer 16

Cells with mutated p53 don’t G1 arrest or repair DNA so proliferate to form a malignant tumour

Question 17

What does E2F do

Answer 17

protein that binds to DNA and stimulates cell to divide

Question 18

What binds to E2F to make it inactive

Answer 18

Rb gene

Question 19

What happens to the Rb gene once it is phosphorylated

Answer 19

Can no longer bind to E2F

Question 20

What are proto-oncogenes

Answer 20

Normal genes that promote normal cell growth and mitosis

Question 21

What do tumour suppressor genes regulate? (anti- oncogenes)

Answer 21

apoptosis and DNA repair

Question 22

How are oncogenes activated

Answer 22

Mutation occurs
dysregulation of proto-oncogene
Turns to oncogene
CAUSE CANCER

Question 23

Describe the Go phase of the cell cycle

Answer 23

Resting phase - cell has left cycle and stopped dividing

Question 24

What 3 phases make up the interphase of the cell cycle?

Answer 24

G1, S, G2

Question 25

Describe the G1 phase of the cell cycle and it's checkpoint

Answer 25

Cells increase in size | G1 checkpoint control mechanism ensures everything is ready for DNA synthesis

Question 26

Describe the S phase of the cell cycle

Answer 26

DNA replication occurs

Question 27

Describe the G2 phase of the cell cycle and it's checkpoint

Answer 27

Gap between DNA synthesis and mitosis where cells continue to grow G2 checkpoint control mechanism ensures that everything is ready for M phase

Question 28

Describe the mitosis phase of the cell cycle

Answer 28

cell growth stops | generates 2 genetically identical daughter cells

Question 29

What does the metaphase checkpoint in mitosis do

Answer 29

Ensures cell is ready to undergo complete division