3 - Oncogenes

Question 1

Difference between benign and malignant

Answer 1

Benign - confined to non-vital organ. Differentiated

Malignant - invades other tissues via blood & lymphatic. Not differentiated

Question 2

Is loss of growth control genetic?

Answer 2

Yes. Passed down from parent to daughter cell

Question 3

Two example of hereditary cancers

Answer 3

Retinoblastoma
Wilm’s tumour

Question 4

What is ataxia telangiectasia

Answer 4

DNA repair deficiency syndrome
Sensitivity to IR

Question 5

What is xeroderma pigmentosum

Answer 5

DNA repair deficiency syndrome
Deficiency in BER, sensitivity to UV

Question 6

Origin of viral oncogenes

Answer 6

Homologous to host genomic sequences
Absence of intronic sequences
Normal cellular counterparts “proto-onco genes”

Question 7

What is the Rous sarcoma virus

Answer 7

The src gene (oncogene)
It encodes for a small protein found to alter the growth pattern of infected cells and render them cancerous

Question 8

How do we know multiple genetic alterations are required for cancers

Answer 8

First clues from tomour viruses - experiment by Peyton Rous (rous sarcoma) on chicken sarcoma in breast tissue

Question 9

How do long latency retroviruses activate cellular proto-oncogenes

Answer 9

insertional mutagenesis
e.g. c-myc proto-oncogene is activated by the avian leukosis virus