Explain how the following mutations would affect transcription of the yeast \(G A L 1\) gene in the presence of galactose. (a) A deletion within the GAL4 gene that removes the region encoding amino acids 1 to 100 . (b) A deletion of the entire \(G A I 3\) gene. (c) A mutation within the \(G A L 80\) gene that blocks the ability of Gal80 protein to interact with Gal3p. (d) A deletion of one of the four UAS elements upstream from the GAL1 gene. (e) A point mutation in the GAL1 core promoter that alters the sequence of the TATA box.

a) Deletion within the GAL4 gene that removes the region encoding amino acids 1 to 100. b) Deletion of the entire GAL3 gene. c) Mutation within the GAL80 gene that blocks the ability of Gal80 protein to interact with Gal3p. d) Deletion of one of the four UAS elements upstream from the GAL1 gene. e) A point mutation in the GAL1 core promoter that alters the sequence of the TATA box. Answer: a) The transcription of GAL1 would likely not occur because the deletion might disrupt GAL4's structure and function, preventing it from binding to UAS elements or activating transcription. b) The transcription of GAL1 would not occur as GAL3 protein is missing, allowing GAL80 to remain bound to GAL4, and inhibiting its activation function. c) The transcription of GAL1 would not be affected in the presence of galactose because the mutated GAL80 would still bind to GAL4, inactivating its function. d) The transcription of GAL1 may be reduced but not completely abolished as the GAL4 protein can still bind to the remaining UAS elements and activate transcription. e) The transcription of GAL1 may decrease or be completely lost, as the alteration in the TATA box might affect the binding of the transcription machinery to the core promoter, leading to inefficient transcription initiation.