Team:Tsinghua-A/Modeling/Part1

The ara operon is regulated by the AraC protein. If arabinose is absent, the dimer AraC protein represses the structural gene by binding to araI 1 and araO 2 and the DNA forms a loop. The loop prevents RNA polymerase from binding to the promoter of the ara operon, thereby blocking transcription .When arabinose is present, arabinose binds AraC and prevents AraC from interacting. This breaks the DNA loop. The two AraC-arabinose complexes bind to the araI site which promotes transcription. When arabinose is present, AraC acts as an activator and promotes the translation of Cre. Then we use Cre-Loxp recombination, a site-specific recombinase technology to carry out inversions in the DNA of cells. The description of the system contains the above mass actions as well as some hill kinetics, Henri-Michaelis-Menten. Since concentration of protein is the integrals of its mRNA, we assume that it is proportional to concentration of mRNA in a previous time. readmore

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We analyze three parameters and the third parameter –the degradation rate of Cre protein –have an obvious effect on the final percent of the genes in different state.readmore

By introducing a feed forward to the system, we increase the percent of the genes flipping to the state we want.And the system is more stable.readmore

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