Question

Of the two classes of genes associated with cancer, tumor-suppressor genes and oncogenes, mutations in which group can be considered gain-of-function mutations? In which group are the loss-of-function mutations? Explain.

Short answer

Answer: Gain-of-function mutations are observed in oncogenes, while loss-of-function mutations are associated with tumor-suppressor genes.

Step-by-step solution

1. Understanding Tumor-Suppressor Genes

Tumor-suppressor genes are responsible for controlling cell growth and preventing the formation of tumors. They act as a brake to stop the uncontrolled growth of cells. When these genes are functioning normally, they can prevent the development of cancer. However, when these genes are mutated, their ability to control cell growth and prevent tumor formation is impaired.

2. Understanding Oncogenes

Oncogenes are mutated versions of normal genes called proto-oncogenes, which play a role in cell division and growth. When a proto-oncogene mutates, it can become an oncogene that promotes uncontrolled cell growth and tumor formation. Oncogenes act as accelerators for cell growth and division, and their mutation can lead to the development of cancer.

3. Identifying Gain-of-Function Mutations

Gain-of-function mutations are changes in a gene that increase or improve the function of the gene. In the context of cancer, gain-of-function mutations typically lead to an increase in cell growth and division. Oncogenes are the result of gain-of-function mutations, as their mutations lead to the overactivation of cell growth and division, promoting the development of cancer.

4. Identifying Loss-of-Function Mutations

Loss-of-function mutations are changes in a gene that decrease or eliminate the function of the gene. In the case of cancer, loss-of-function mutations usually involve the inability to control cell growth and division. Tumor-suppressor genes are associated with loss-of-function mutations, as their mutations lead to a decreased ability to prevent tumor formation and control cell growth.

5. Concluding the answer

In conclusion, gain-of-function mutations are observed in oncogenes, leading to an increase in cell growth and division, and the development of cancer. Loss-of-function mutations are associated with tumor-suppressor genes, as their mutations result in a decreased ability to control cell growth and prevent tumor formation.