Flashcards in Topic F2 Deck (7):
What is an oncogene?
- A mutation in one or more copies of a proto-oncogene that causes a gain function mutation that causes the cancer cell to grow and divide inappropriately
What is a proto-oncogene?
- Normal cellular genes that promote cell growth and cell division
- oncogenes are mutated forms of proto-oncogenes that lead to an increased activity of gene products
What are the 3 main ways a proto-oncogene can become an oncogene?
- An activating mutation in a DNA coding sequence e.g. an overactive protein
- Gene amplification e.g. over-expressed receptors
- Chromosome re-arrangement: can produce fusion proteins that are over produced and highly oncogenic
Are oncogenes dominant or recessive?
- Dominant; a single copy of the mutated cancer gene can predispose cancer by a gain of function mutation
Can viruses mutate host proto-oncogenes to oncogenes?
Yes, the proto-oncogene may be altered following the insertion of the viral gene either upstream of the proto-oncogene or within the coding sequence e.g. papillomavirus causes cervical cancer
What is the largest group of oncogenes?
- Tyrosine kinase receptors that are mutated or over expressed can cause cellular transformation (cancer)