Oncoviruses

Question 1

Oncoviruses contain ___________________ to ________________.

Answer 1

Reverse transcriptase

Turn RNA into DNA

Question 2

Retroviruses have the potential to cause:
•
•
To promote _______________________.

Answer 2

Loss of gene function
DNA damage

Tumour formation

Question 3

The rous sarcoma virus has ___________________ due to an error following ___________ and __________.

As a result, ________________ is over expressed in effected cells.

Answer 3

Acquired part of the sequence encoding src (kinase domain)

Integration and mRNA splicing

Src kinase domain

Question 4

Unregulated expression of src results in __________ of _________ (cytoskeleton protein in focal adhesion plaques) and debundling of _________________. Loss of growth control also results from ________________________.

Answer 4

Phosphorylation
Vinculin
Actin filaments
Uncontrolled signalling to the nucleus

Question 5

What is an oncogene?

Answer 5

A gene whose abnormal expression/altered gene product directly determines the production of a malignant phenotype

Gain of function

Question 6

What is a proto-oncogene?

Answer 6

The cellular homologue from which the oncogene is derived

Question 7

What is a tumour suppressor?

Answer 7

A gene that encodes a protein that restricts cell growth

Loss of function results in tumour formation

Question 8

A proto-oncogene can become an oncogene via:

• _______________leading to a hyperactive protein made in normal amounts e.g._____
• gene amplification: _______________________ e.g. Jun
• _________________:
• nearby strong enhancer causes_________________ e.g. Myc in burkitts lymphoma
• ________________ e.g. Bcr/abl __________________

Answer 8

Deletion or point mutation
Ras
Normal gene product greatly overproduced 
Chromosome rearrangement 
Normal protein greatly overproduced 
Hyperactive fusion protein
Philadelphia chromosome

Question 9

What are the 4 main groups of oncogenes?

Answer 9

• Growth factors
• Receptors
• Transducers
• Transcription factors