A system for propagating information that includes: (A) a nucleic acid structure that comprises an incompletely base-paired duplex domain; (B) at least one polynucleotide displacement molecule capable of effecting binding with the nucleic acid structure under hybridizing conditions, such that upon binding the nucleic acid structure undergoes a transition in energy state due to a branch migration reaction involving the duplex domain producing an output polynucleotide sequence; and (C) at least one polynucleotide clashing molecule capable of binding with the nucleic acid structure under hybridizing conditions, such that when bound the nucleic acid structure and the clashing molecule prevent the binding of the polynucleotide displacement molecule; wherein: at least one of the displacement molecule and the nucleic acid structure has a chemical modification relative to a first reference molecule that comprises natural nucleosides in the same sequence as the displacement molecule or nucleic acid structure comprising the chemical modification, such that there is a higher binding affinity between the displacement molecule and the nucleic acid structure relative to a reference binding between the displacement molecule or the nucleic acid structure and the first reference molecule; and/or at least one of the clashing molecule and the nucleic acid structure has a chemical modification relative to a second reference molecule that comprises natural nucleosides in the same sequence as the clashing molecule or nucleic acid structure comprising the chemical modification, such that there is a lower binding affinity between the clashing molecule and the nucleic acid structure relative to a reference binding between the clashing molecule or the nucleic acid structure and the second reference molecule. (A) a nucleic acid structure that comprises an incompletely base-paired duplex domain; (B) at least one polynucleotide displacement molecule capable of effecting binding with the nucleic acid structure under hybridizing conditions, such that upon binding the nucleic acid structure undergoes a transition in energy state due to a branch migration reaction involving the duplex domain producing an output polynucleotide sequence; and (C) at least one polynucleotide clashing molecule capable of binding with the nucleic acid structure under hybridizing conditions, such that when bound the nucleic acid structure and the clashing molecule prevent the binding of the polynucleotide displacement molecule; at least one of the displacement molecule and the nucleic acid structure has a chemical modification relative to a first reference molecule that comprises natural nucleosides in the same sequence as the displacement molecule or nucleic acid structure comprising the chemical modification, such that there is a higher binding affinity between the displacement molecule and the nucleic acid structure relative to a reference binding between the displacement molecule or the nucleic acid structure and the first reference molecule; and/or at least one of the clashing molecule and the nucleic acid structure has a chemical modification relative to a second reference molecule that comprises natural nucleosides in the same sequence as the clashing molecule or nucleic acid structure comprising the chemical modification, such that there is a lower binding affinity between the clashing molecule and the nucleic acid structure relative to a reference binding between the clashing molecule or the nucleic acid structure and the second reference molecule. <EOS>