Question

Gene A encodes protein A in a prokaryotic organism: A genetic engineer excises a promoter sequence for gene A from the DNA and reinserts at the other end of gene A, oriented so that an RNA polymerase binding at the promoter will transcribe across gene A. Will the mRNA synthesized by the RNA polymerase still possess a sequence that produces a functional protein A? Why or why not?

Answer 1

If the promoter sequence for gene A is reinserted in the opposite orientation, the mRNA synthesized by the RNA polymerase will not produce a functional protein A.

Step-by-step explanation:

If the promoter sequence for gene A is excised from the DNA and reinserted in the opposite orientation, the mRNA synthesized by the RNA polymerase will not possess a sequence that produces a functional protein A.

The reason for this is that the orientation of the promoter sequence determines the direction in which RNA polymerase binds and transcribes the gene. The promoter sequence provides the necessary signals for the initiation of gene transcription. By reinserting the promoter at the other end of gene A in the opposite orientation, it will not be recognized by the RNA polymerase, leading to an incorrect transcription of the gene and the production of a non-functional protein A.