The GAL gene system discovered in yeast is an inducible syst…

The GAL gene system discovered in yeast is an inducible system in which the presence of galactose induces expression of genes that are regulated by GAL4. For GAL4 to initiate transcription, what type of sequence must be present, adjacent to the gene(s) to be transcribed?

Which of these structures are purines? [Text describing the…

Which of these structures are purines? [Text describing the images: (A) shows two rings attached to each other, one with 4 carbon and two nitrogen, and the other with 3 carbon and 2 nitrogen; (B) shows two rings attached to each other, one with 4 carbons and two nitrogen, and the other with 3 carbons and 2 nitrogen; (C) shows a ring with 4 carbons and 2 nitrogen; (D) shows a ring with 4 carbons and 2 nitrogen; (E) shows a ring with 4 carbons and 2 nitrogen]