FIGURE 1 

Comparison of whole-cell and cell-free synthetic biology. (A) Global cellular resources support the operation of synthetic circuits in whole-cell synthetic biology, but also provide subtle pathways for interactions between otherwise unconnected gene circuits. Much of transcriptional regulation is achieved through protein–DNA interactions. (B) The cell-free synthetic biology approach reported by Kim et al removes global resources to support gene circuit operation, translation, and protein transcription factors. Transcriptional regulation is achieved by the competing actions of single-stranded DNA activators and complementary strands of RNA.