Final answer:
6S RNA controls gene expression by binding to and sequestering RNA polymerase, which is part of prokaryotic regulatory mechanisms involving stem-loop structures in mRNA.
Step-by-step explanation:
6S RNA regulates transcription by sequestering RNA polymerase. This regulation is part of a broader mechanism used by prokaryotes, where the formation of stem-loop structures at the 5' end of mRNA molecules influences the completion of transcription and translation. In the example of riboswitches, small molecules like guanine can bind to these stem-loop structures, signaling the need to regulate gene expression. If the concentration of such a molecule is high, it can lead to the dissociation of RNA polymerase and the nascent mRNA from the DNA template, resulting in the premature termination of transcription. This self-regulating mechanism is essential for maintaining homeostasis within the cell.