PBL ILO’s

Question 1

The normal cell cycle and how abnormalities can cause cancer

Answer 1

The cell cycle is a four-stage process in which:

1) The cell increases in size (gap 1, or G1, stage)

2) Copies its DNA (synthesis, or S, stage)

3) Prepares to divide (gap 2, or G2, stage)

4) and divides (mitosis, or M, stage).

Cancer is the result of unchecked cell division caused by a breakdown of the mechanisms regulating the cell cycle.
• The loss of control begins with a change in the DNA sequence of a gene that codes for one of the regulatory molecules. Faulty instructions lead to a protein that does not function as it should.

Question 2

Tumour suppressor gene

Answer 2

Tumor suppressor genes represent the opposite side of cell growth control, normally acting to inhibit cell proliferation and tumor development.

In many tumours, these genes are lost or inactivated, thereby removing negative regulators of cell proliferation and contributing to the abnormal proliferation of tumor cells.

Question 3

Oncogene and proto-oncogene

Answer 3

Cancer is a disease of inappropriate cell proliferation.

An oncogene is a mutated gene that has the potential to cause cancer. Before an oncogene becomes mutated, it is called a proto-oncogene, and it plays a role in regulating normal cell division.

Question 4

Name some genetic disorders that contribute to cancer that runs in families.

Answer 4

• Mutation in P53 (li-fraumeni syndrome), lynch syndrome, retinoblastoma, familial adenomatous polyposis

Question 5

Describe the process of oncogenesis

Answer 5

• Initiation
  
  • Promotion
  • Malignant conversion
  • Tumour progression