A clocked DNA – based replicator Seung Hwan Lee Seung Hwan Lee Bernard Yurke and David Zhang

Introduction Reproducing ability Reproducing ability  DNA serves as its own template to make copies itself. Replication by living organism Replication by living organism  Exponential growth process  Easy scale up  Imperfect process – Darwinian evolution Synthetic system - Not using polymerases Synthetic system - Not using polymerases  Parabolic process – product inhibition

DNA based nanomachine Using the hybridization of energy strand to activate the machine Using the hybridization of energy strand to activate the machine Strand displacement through competitive binding mediated by toeholds is used to return the machine. Strand displacement through competitive binding mediated by toeholds is used to return the machine. Stepwise feeding Stepwise feeding  Meaning of clocked  The operator controls when the machine advances to its next state through the addition of the appropriate DNA strand to solution containing the machines.

The replicator Linker strand Recognition group

The replication machinery Supplying the energy The removal of the replication machinery

The replication step 1  The addition of energy strands  Pulling the structure into two part  The replicator hybridize with the replication machinery.

The replication step2 The addition of new monomer The addition of new monomer

The replication step3 The removal of replication machinery The removal of replication machinery  The removal strands hybridize with The toeholds of replication machinery.  The replication machinery strands are double-strand. Neutral to the further process Neutral to the further process

Conclusion Solving the problem of product inhibition by ladder like structure Solving the problem of product inhibition by ladder like structure  Imposing the geometrical constraints  Final replication machinery has double stranded structure. Exponential amplification – error prone Exponential amplification – error prone  Circumstances could be devised where strands with different base sequences could compete with each other.  Darwinian evolution – mutation, selection

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