Topic F2 Flashcards Preview

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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)


What are some examples of oncogenes

- Erb-B
- K-ras
- c-myc
- N-myc