Final answer:
Oncogenes are mutated genes that promote tumor formation by causing uncontrolled cell growth and division. Proto-oncogenes, which are normally responsible for cell growth, can become oncogenes when they mutate, leading to the development of cancer. The development of cancer involves multiple mutations in both oncogenes and tumor suppressor genes.
Step-by-step explanation:
Oncogenes are mutated forms of genes that promote tumor formation. When a gene mutates and becomes an oncogene, it promotes the uncontrolled growth and division of cells, leading to the development of cancer. These mutated genes are usually dominant alleles that contain gain-of-function mutations, resulting in constitutively activated proteins that override the normal control mechanisms of the cell cycle.
Proto-oncogenes are normal genes that promote cell growth and reproduction. However, when they mutate into oncogenes, they become continuously active and cause cells to divide uncontrollably. This can result in the formation of tumors and the development of cancer.
The development of cancer involves multiple mutations in both oncogenes and tumor suppressor genes. Tumor suppressor genes inhibit cell division, survival, and other properties of cancer cells. When these genes are inactivated due to mutations, the malignant phenotype of cancer cells is promoted. Ultimately, the transformation of a normal cell into a cancer cell requires multiple genetic changes in various genes.