Question

Which of the following best defines an oncogene?

• A. An oncogene is a dominantly expressed mutation which gives a cell a growth or survival advantage
• B. An oncogene codes for a mutated form of a protein which forms part of a signal transduction pathway
• C. An oncogene codes for a protein which prevents the cell from undergoing apoptosis
• D. An oncogene codes for a cell cycle control protein

Answer 1

Answer: (A)

An oncogene is a dominantly expressed mutation which gives a cell a growth or survival advantage

Answer 2

Oncogenes refer to genes that has the potential to cause cancer and are dominant at the cellular level. Proto oncogenes are the normal genes. These genes code for proteins that are capable of stimulating cell growth and division. In normal tissues and organisms, such growth stimulating proteins are regulated, so, that growth is appropriately limited. However, mutations in these genes may result in loss of growth regulation, leading to uncontrolled cell proliferation and tumour development. Oncogenes are dominant, because a mutation of only one of the cell's two copies of that gene can lead to tumour formation.