RNA is able to control its own transcription, given the right trigger. See how the RNA-based riboswitch twists into a tangle in the presence of the right ligand.

Metabolite-sensing mRNAs, or riboswitches, specifically interact with small ligands and direct expression of the genes involved in their metabolism. Riboswitches contain sensing ‘aptamer’ modules ...

Genetic switches could play a role in creating complex eukaryotic genetic circuits for programmed cell-free systems or artificial cells.