Gene expression and cancer

Question 1

What are the characteristics of a maliganant tumour?

Answer 1

Can grow to large size
Grow rapidly
Larger and darker nucleus
Unspecialised cells
Can perform metastasis
No capsule
Life threatening

Question 2

What are the characteristics of a benign tumour?

Answer 2

Can grow to a large size
Grow slowly
Often specialised
Produce adhesion molecules so does not spread
Surrounded by capsule so compact
Less life threatening

Question 3

Describe how a secondary tumour can form from a primary tumour via metastasis

Answer 3

Primary tumour develops lymphatic and blood vessels via capillarisation as it enlarges
Tumour cells squeeze into these vessels and circulate around body
Tumour cells adhere to vessel walls and squeeze through, forming distant metastases

Question 4

What 2 genes contribute to cancer

Answer 4

Oncogenes
Tumour suppressor genes

Question 5

What do proto-oncogenes do?

Answer 5

Stimulate cells to divide by producing proteins (growth factors) that stimulate cell division

Question 6

What are oncogenes

Answer 6

Mutated proto-oncogenes that is permanently activated

Question 7

In what 2 ways do oncogenes cause uncontrolled cell division?

Answer 7

Permanently activate receptor protein on cell surface membrane , causing cell division to be kept switched on

Coding for an excess amount of growth factor, stimulating excess cell division

Question 8

What is the function of tumour suppressor genes?

Answer 8

Slow down cell division, repair mistakes in DNA and stimulate apoptosis in cells

Question 9

What happens if Tumour suppressor genes are inactivated?

Answer 9

Stops inhibition of cell division so it becomes uncontrolled

Question 10

Describe how hypermethylation can cause cancer

Answer 10

Hypermethylation occurs in promoter region of tumour suppressor genes
Transcription of promotor regions of genes is inhibited
Tumour suppressor gene is inactivated
Leads to uncontrolled cell division and tumour formation

Question 11

Explain why an increase in oestrogen concentration increase the likely hood of developing breast cancer

Answer 11

After menopause, breasts produce greater conc of oestrogen
Oestrogen binds to transcription factors that activates genes promoting cell division
Cell division becomes uncontrolled, causing tumour formation