The functional activity of the KRAS protein promotes cell proliferation and is often mutated in leukemia (cancer of a type of blood cell).In a B cell leukemia, a clinical researcher identifies a G → A transition at the second base of codon 12, resulting in a glycine → aspartic acid substitution in the protein.In normal cells, KRAS protein function can be activated and suppressed by the activity of other proteins.In contrast, in the leukemic cells, KRAS protein function is resistant to suppression.This is an example of a _______ mutation generating a_______-of-function mutation.

Question

Quizplus · Accepted Answer

The mutation described in this scenario is a missense mutation, as it results in a substitution of one amino acid for another. Specifically, the substitution of glycine to aspartic acid at position 12 of the KRAS protein. This mutation results in a gain-of-function mutation, as the KRAS protein function promotes cell proliferation, and the mutation makes it resistant to suppression. Therefore, the best choice is C: missense; gain.

The Functional Activity of the KRAS Protein Promotes Cell Proliferation