CONSPECTUS: The impact of nucleic acid nanotechnology in terms of transforming motifs from biology in synthetic and translational ways is widely appreciated. But it is also emerging that the thinking and vision behind nucleic acids as construction material has broader implications, not just in nanotechnology or even synthetic biology, but can feed back into our understanding of biology itself. Physicists have treated nucleic acids as polymers and connected physical principles to biology by abstracting out the molecular interactions. In contrast, biologists delineate molecular players and pathways related to nucleic acids and how they may be networked. But in vitro nucleic acid nanotechnology has provided a valuable framework for nucleic acids by connecting its biomolecular interactions with its materials properties and thereby superarchitecture ultramanipulation that on multiple occasions has pre-empted the elucidation of how living cells themselves are exploiting these same structural concepts. This Account seeks to showcase the larger implications of certain architectural principles that have arisen from the field of structural DNA/RNA nanotechnology in biology. Here we draw connections between these principles and particular molecular phenomena within living systems that have fed in to our understanding of how the cell uses nucleic acids as construction material to achieve different functions. We illustrate this by considering a few exciting and emerging examples in biology in the context of both switchable systems and scaffolding type systems. Due to the scope of this Account, we will focus our discussion on examples of the RNA scaffold as summarized. In the context of switchable RNA architectures, the synthetic demonstration of small molecules blocking RNA translation preceded the discovery of riboswitches. In another example, it was after the description of aptazymes that the first allosteric ribozyme, glmS, was discovered. In the context of RNA architectures as structural scaffolds, there are clear parallels between DNA origami and the recently emerging molecular mechanism of heterochromatin formation by Xist RNA. Further, following the construction of well-defined 2D DNA-protein architectures, the striking observation of remarkably sculpted 2D RNA-protein hydrogel sheets in Caenorhabditis elegans speaks to the in vivo relevance of designer nucleic acid architectures. It is noteworthy that discoveries of properties in synthetic space seem to precede the uncovering of similar phenomena in vivo.