Gene expression and cancer

Question 1

Name the 2 types of tumor

Answer 1

• malignant

- benign

Question 2

Give 3 properties of benign tumors

Answer 2

• grow very slowly
• cells are often specialised
• cells are surrounded by a capsule of dense tissue and
  so remain a compact structure
• localized effects on body
• they do not spread

Question 3

Give 3 properties of malignant tumors

Answer 3

• grow to a large size
• grow very rapidly
• cells become unspecialized
• do not produce cell adhesion molecules and so spreads round the body (metastasis)
• more likely to be life threatening
• often reoccur after treatment

Question 4

Name two main genes involved in cancer?

Answer 4

Oncogenes and tumor suppressor genes

Question 5

What do tumor suppressor genes do?

Answer 5

• slow down cell division
• repair mistakes in DNA
• controls apoptosis

Question 6

What do proto-oncogenes do?

Answer 6

• stimulate a cell to divide

- and DNA to replicate

Question 7

How can cancer be caused?

Answer 7

receptor proteins on the C.S.M. can be permanently activated, so that cell division is switched on even in absence of growth factors.

the oncogene may code for a growth factor that is then produced in excessive amounts.

Question 8

How can abnormal methylation lead to cancer?

Answer 8

• hypermethylation occurs in promoter region of tumor suppressor gene
• this leads to tumor suppressor begin inactivated