Schematic representation of the functionality of the Constructor. The user fills the codes of the parts of the query circuit (based on the vocabulary of the Registry). Next, the Constructor finds all arrangements of the Transcription Units (TUs). The functionality of the gene circuit is supposed to be independent of the order of the different TUs, and the Constructor tries to build all possible arrangements from all BioBrick parts in the Registry. Finally, the Constructor recommends up to three sets of BioBrick parts with which the genetic circuit can be made, based on the smallest number of parts, aiming for the fewest cloning steps. The symbols of the various parts (promoter, ribosomal binding site (RBS), coding sequence (CDS) and terminator) are explained in the lower panel.