Which of the following statements is false about oncogenes?
A ecDNA creates recessive mutations which causes increased oncogene production
B Mutations in the coding sequence can result in oncogene hyperactivity
C Chromosome rearrangement can result in extra activity of the oncogene
D Aneuploidy is a source of oncogene over expression
E Oncogene always display dominant mutations
The correct answer and explanation is:
The correct answer is: E. Oncogene always display dominant mutations.
Oncogenes are genes that have the potential to cause cancer when they are mutated or expressed at abnormally high levels. These mutations can lead to uncontrolled cell growth and division, which is a hallmark of cancer. Oncogenes are typically associated with dominant mutations, meaning that a single altered copy of the gene is enough to promote cancerous growth, even if the other copy of the gene is normal.
This characteristic is in contrast to tumor suppressor genes, which usually require both copies of the gene to be mutated (a recessive mutation) in order to lose their normal function. When a dominant mutation occurs in an oncogene, the altered gene product may function inappropriately, either by promoting cell division or by inhibiting cell death, leading to the formation of a tumor. For instance, a point mutation in the Ras gene can result in a protein that is continuously active, promoting cell proliferation even in the absence of growth signals.
In many cases, the expression of an oncogene does not necessarily require both alleles to be mutated; it can happen if the oncogene is overexpressed due to genetic amplification, translocation, or other mechanisms. This overexpression can cause the cell to behave as though the gene is permanently “turned on,” driving the cell towards cancerous growth. Oncogenes are therefore important targets for cancer therapy, as controlling their activity can help to limit tumor progression.