I will describe the modeling of several genetic regulatory modules in cells and analyze the effects of competition [1], feedback and fluctuations [2] in these systems. The genetic networks to be considered involve a combination of transcriptional regulation, post-transcriptional regulation by small non-coding RNAs and protein-protein interactions. The effects of competition, feedback and fluctuations on each one of these regulation mechanisms will be discussed. I will present results obtained using a combination of deterministic and stochastic methods, including rate equations, direct integration of the master equation and Monte Carlo simulations.

[1] Competition between small RNAs: a quantitative view, A. Loinger, Y. Shemla, I. Simon, H. Margalit and O. Biham, Biophys. J. 102, 1712 (2012)        

[2] Analysis of genetic toggle switch systems encoded on plasmids, A. Loinger and O. Biham, Phys. Rev. Lett. 103, 068104 (2009)