The GAL gene system in yeast is used to metabolize galactose.In the presence of galactose,the GAL genes are expressed; however,in the absence of galactose,the GAL genes are repressed.A yeast mutant is discovered that continuously expresses the GAL genes in the presence or absence of galactose.Which GAL gene is likely mutated?

Question

Quizplus · Accepted Answer

GAL80 is the correct answer because it normally functions to inhibit GAL4, the activator of the GAL genes. If GAL80 is mutated in a way that it loses its function, GAL4 remains active regardless of the presence of galactose, leading to continuous expression of the GAL genes.

The GAL Gene System in Yeast Is Used to Metabolize