Regulation of Gene Transcription Practice Test

In bacteria, gene R is transcribed from a promoter that requires an activator bound upstream to help recruit RNA polymerase. Under low oxygen, the activator binds DNA and transcription increases. A point mutation occurs in the activator’s DNA-binding domain so it cannot bind the upstream site, but the promoter sequence is unchanged. Which result is most likely under low oxygen?

In a eukaryotic nucleus, transcription factor TF binds a promoter-proximal element of gene Z and increases transcription when TF is phosphorylated. A signaling kinase phosphorylates TF in response to hormone H. In cells treated with H, TF is present but gene Z mRNA does not increase. Sequencing shows TF is unchanged, but the kinase has a loss-of-function mutation. Which change would most likely increase transcription of gene Z in response to H?