What does the term "oncogene" refer to?

The term "oncogene" refers specifically to a mutated form of a proto-oncogene, which is a normal gene involved in cell growth and division. When a proto-oncogene undergoes mutations or is overexpressed, it can become an oncogene. This alteration leads to the protein produced by the oncogene being either overactive or excessively abundant, which pushes the cell toward uncontrolled division and proliferation—hallmarks of cancer.

The distinction between proto-oncogenes and oncogenes is crucial; while proto-oncogenes normally regulate healthy cell growth and division, oncogenes can malfunction and encourage tumor formation and cancer progression. This is a pivotal concept in cancer biology, as the activation of oncogenes is one of the several genetic changes that contribute to the development of cancer.

In relation to the other options, a gene that prevents cell division corresponds to tumor suppressor genes rather than oncogenes, and genes that suppress tumor formation or repair DNA damage address different mechanisms in cancer prevention and repair, highlighting the diverse roles of various gene types in relation to cancer progression and treatment.