Regulation of gene expression in eukaryotes - Lessons from yeast: the GAL system

3 important questions on Regulation of gene expression in eukaryotes - Lessons from yeast: the GAL system

To make use of extracellular galactose, yeast imports the sugar and converts it into a form of glucose that can be metabolized. Several genes—..., ..., ... and ...—in the yeast genome encode enzymes that catalyze steps in the biochemical pathway that converts galactose into glucose. Three additional genes— ..., ... and ...—encode proteins that regulate the expression of the enzyme genes.

GAL1, GAL2, GAL7, GAL10
GAL3, GAL4, GAL80

True or false: just as in the lac system of E. coli, the abundance of the sugar determines the level of gene expression in the biochemical pathway of yeast.

True

In yeast cells growing in media lacking galactose, the GAL genes are largely silent/actively transcribed.

Silent
In the presence of galactose (and the absence of glucose), the GAL genes are induced.

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