What does a mutation in the Ras gene that causes it to behave as if it is constantly bound to GTP cause?

A mutation in the Ras gene that results in its constant activation, mimicking a state of being perpetually bound to GTP, leads to the gene functioning as an oncogene. Oncogenes are mutated forms of proto-oncogenes, which are normal genes involved in cell growth and division. When proto-oncogenes are mutated or expressed at high levels, they can become oncogenic, driving unchecked cell proliferation and contributing to cancer development.

In this specific case, the Ras mutation results in a gain-of-function phenotype, where the protein is always active, promoting pathways that lead to cell division and survival even in the absence of normal growth signals. This state of continuous activation is characteristic of oncogenes that push cells toward an aggressive growth phenotype, a hallmark of cancer cells.

Therefore, the mutation in the Ras gene not only identifies it as an oncogene due to its gain-of-function characteristic but also highlights its role in promoting tumorigenesis, distinguishing it from tumor suppressors, which work to restrain cell growth and prevent the occurrence of tumors.