The ras proto-oncogene can become an oncogene by a single point mutation that alters its protein product to have _______ activity.

Question

Quizplus · Accepted Answer

The Ras proto-oncogene regulates cell division by transmitting extracellular signals into the cell, activating the MAPK/ERK pathway. However, if a point mutation occurs in the gene, it can become oncogenic and contribute to cancer development. This occurs because the mutated protein product (oncogenic Ras) becomes constitutively active and no longer requires external signals to activate the MAPK/ERK pathway. Specifically, the mutation causes a change in the protein's structure that prevents GTP hydrolysis, leading to continuous activation of downstream signaling pathways. This constitutive activation of the Raf kinase leads to hyperproliferation of cells, which can eventually lead to cancer. Therefore, Choice B, constitutive Raf-activation, is the correct answer.

The Ras Proto-Oncogene Can Become an Oncogene by a Single