Final answer:
Oncogenes behave in a dominant manner, as they produce a mutated protein that prompts cancerous growth even if only one gene copy is altered. Tumor suppressor genes are usually recessive, requiring both copies to be mutated for cancer progression.
Step-by-step explanation:
Oncogenes typically behave in a dominant manner because they contain gain-of-function mutations that result in an active protein capable of promoting cell division in the absence of normal regulatory signals. Even a single copy of a mutated proto-oncogene can drive the transformation into an oncogene, overriding the normal cell growth regulation and leading to cancerous growth. In contrast, tumor suppressor genes generally act in a recessive manner, requiring both alleles to be affected before the loss of function in cellular growth control takes place. However, in some instances, a single mutated tumor suppressor gene can exhibit a dominant negative effect, disabling the normal function of the non-mutated copy.
Both oncogenes and tumor suppressor genes are integral to the cell's own "cruise control system," with oncogenes acting as an overactive accelerator and tumor suppressor genes functioning as the necessary brakes. Typically, cancer development necessitates multiple mutations, including the activation of oncogenes and the deactivation of tumor suppressor genes. Without enough functional tumor suppressors, the balance tips in favor of unregulated cell proliferation, signaling a potential development towards cancer.