3.8.2.3 Gene expression and cancer

Question 1

Tumour definition

Answer 1

Tumours are abnormal cell growths resulting from uncontrolled cell division and can occur in any tissue or organ

Question 2

Definition of Cancer

Answer 2

Diseases caused by the growth of tumours are collectively known as cancers.

Question 3

Benign tumour vs Malignant tumour characteristic

Answer 3

Benign tumor
- Non-cancerous (adhesive)
- Capsulated (compacted, can remove by surgery)
- Non-invasive
- Slow growing
- Do not metastasize (spread) to other parts of the body
- Cells are normal

Malignant tumor
- Cancerous
- Non-capsulated
- Fast growing
- Metastasize (spread) to other parts of the body
- Cells have large, dark nuclei: may have abnormal shape
- grow projection, develope own blood supply
- more likely reoccurence, danger surgery

Question 4

Use/ definition of proto-oncogenes

Answer 4

Proto-oncogenes code for proteins that stimulate the cell cycle and promote cell growth and proliferation.

Question 5

Use/ definition of Tumour suppressor genes

Answer 5

Tumour suppressor genes code for proteins that repress cell cycle progression and promote apoptosis or cause cell death

Question 6

Most cancers are caused by mutations to two basic classes of genes

Answer 6

proto-oncogenes and tumour suppressor genes

Question 7

two type of abnormal methylation on genes

Answer 7

Hypermethylation (increased methylation) in the promoter region decreases the expression of the tumour suppressor gene.

Hypomethylation (reduced methylation) in the promoter region increases the expression of oncogenes.

Question 8

How alternation in tumour suppressor gene can develop cancer

Answer 8

Mutations in the tumour suppressor genes can occur
As a result, a protein with a different primary and tertiary structure could be produced, which causes a loss in function.

Increased methylation of tumour suppressor genes can occur
As a result, the tumour suppressor genes are not expressed / transcribed and translated.

This can result in uncontrolled cell division.

Question 9

How increased of methylation can lead to cancer

Answer 9

Methyl groups are added to cytosine bases on DNA on both copies of the tumour suppressor gene.
The decreases the transcription of the tumour suppressor gene.
The proteins of this gene slow down mitosis, so fewer proteins will result in an increase in mitosis and cell division, leading to uncontrolled cell growth and cancer.

Question 10

How alternation in proto-oncogene can develop cancer

Answer 10

Mutations in the proto-oncogene can occur
As a result, more protein is produced
decrease methylation of proto-oncogene can occur
As a result, the tumour onco genes are over expressed / transcribed and translated.
This can result in uncontrolled cell division.