Before revision:  Here we study the origin of stochasticity qualitatively in a network of two genes using stochastic simulation method and argued that stochasticity in gene expression may be a choice of cellular system for optimum output with minimum energy cost.
After revision:  Here we study the origin of stochasticity qualitatively in a network of two genes using stochastic simulation method and argued that stochasticity in gene expression may be a choice of cellular system for protein synthesis with minimum energy cost.