Mutation

Question 1

4 ways of how mutation arises?

Answer 1

1. Over-expression of proto-oncogene
2. Under-expression of tumour suppressor genes
3. Mutation in gene responsible for apoptosis
4. Exposure to mutagens

Question 2

Define proto-oncogene

Answer 2

stimulatory gene and can be made overactive or active at inappropriate times

-usually dominant as a single copy of mutated gene is sufficient to px s stimulatory effect

Question 3

Proto-oncogene codes for? to promote cell growth

Answer 3

• growth factors
• growth factor receptors
• TF
• protein kinases
• inhibitors of apoptosis

Question 4

Proto-oncogene under normal conditions?

Answer 4

-code for proteins that send a signal to the nucleus to stimulate cell division
-> signal transduction pathway
=> increased cell proliferation

Question 5

Define tumour suppressor gene

Answer 5

Function to prevent inappropriate cell cycle progression suppressing cell growth and proliferation

Question 6

4 ways of TSG pdts inhibit excessive cell growth and division?

Answer 6

1. Halting cell division if DNA is damaged
2. Triggering DNA repair mechanisms, preventing cells from accumulating DNA damage
3. Maintaining cell-to-cell adhesion/ cell anchorage to extracellular matrices
4. Cell signalling pathways to inhibit suppressor genes

Question 7

What happen when TSG loses its function?

Answer 7

-decrease normal activities

-increase normal activities
-> no longer result in inhibition of cell division
=> uncontrolled cell division

DNA damages remains

Question 8

Function of p53

Answer 8

-encodes for a special TF that binds to enhancer to increase transcription rates

Question 9

Induction of p53

Answer 9

• activate genes that promote DNA repair
• activate genes that arrest cell division and may generally repress other genes
• activate genes that promote apoptosis

Question 10

What is chromosomal translocation?

Answer 10

Chromosomes have broken and rejoined incorrectly

Eg: translocated proto-oncogene ends up next to active promoter

Question 11

Reciprocal translocation

Answer 11

• shortened version of chromosome 22

- > translocation causes abnormal fusion protein

Question 12

What are the six critical genes?

Answer 12

1. DNA repair genes
2. TSG
3. P-O
4. Genes that regulate apoptosis
5. Genes that maintain telomeres
6. Genes that stimulate angiogenesis and metastasis

Question 13

What is a malignant tumour?

Answer 13

-mass of fast growing cells

Question 14

Describe invasion

Answer 14

• cells in malignant tumour cell no longer respond to normal cellular control mechanism
• spread to neighbouring tissues from Pri tumour

Question 15

Describe metastasis

Answer 15

-cells travel to a distinct tissues, establishing secondary tumour

Question 16

Describe angiogenesis

Answer 16

• blood or lymphatic system
• creation of new blood vessels by tumour occurs at tumour needed an adequate supply of oxygen and nutrients

=> increased blood supply provides additional nutrients
=> further accelerated tumour growth and metastasis