At any given moment in the human body, in about 30 trillion cells, DNA is being “read” into molecules of messenger RNA, the intermediary step between DNA and proteins, in a process called transcription. Scientists have a pretty good idea of how transcription gets started: Proteins called RNA polymerases are recruited to specific regions of the DNA molecules and begin skimming their way down the strand, synthesizing mRNA molecules as they go. But part of this process is less-well understood: How does the cell know when to stop transcribing? Now,…
