Question

Cancer-promoting mutations are likely to have different effects on the activity of proteins encoded by protooncogenes than they do on proteins encoded by tumour suppressor genes. Explain.

Short answer

Cancer-causing mutation makes the protooncogenes overactive. In the tumor suppressor gene, cancer-causing mutation makes the gene non-functional.

Step-by-step solution

Definition of cancer

Cancer is the uncontrolled proliferation of cells resulting in the accumulation of cell mass known as a tumor. Cancer loses control over the cell cycle regulation and normal activity of the cell. Cancer can migrate from the site of infection to secondary sites.

Step 2: Cancer-causing mutation

The mutation is the change that occurs at the genetic level that results in harmful effects on the living organism. Mutation occurring in the gene's coding region may result in cancer formation, known as cancer-causing mutation.

Effect of mutation of protooncogenes and tumor suppressor genes

Protooncogenes are normal genes present in the body. The mutation in this type of gene can convert it into an oncogene. An oncogene is the cancerous form of protooncogene. Cancer formation occurs due to the overactivation of protooncogene that loses control over gene expression.

Tumor suppressor genes are the genes that work over cell division, repair mechanism, and cell apoptosis. When a mutation occurs in this, it can suppress the activity of the tumor suppressor gene that becomes non-functional.

Hence, the mutation of protooncogene results in its overactivation. The mutation of the tumor suppressor gene results in the non-functional gene product.