中文摘要：

被λ噬菌体感染的大肠杆菌是研究生物基因调控网络的重要模板之一．根据该调控系统操纵子与调控蛋白相互作用特点，利用热力学配分函数描述调控蛋白与操纵子的结合概率，在给出该调控系统的动力学分岔的基础上．计算系统各定态的热力学熵．结果显示，溶源态和裂解态较鞍点和分岔点具有更低的熵值，且溶源态的熵最低，说明处于溶源态的系统具有更高的生物序．

英文摘要：

The system of Escherichia coli infected by λ phage is one of the templates for quantitative study of regulated networks. In this article, according to the characteristics of the interactions between operators and regulators, the probabilities of regulators binding to operators are described by thermodynamic partition function. On the basis of bifurcation analysis of this regulated network, the entropies of stationary states are calculated. Results show that the entropies of both lysogenic state and lyric state are lower than those of saddle-point and bifurcation point states. Moreover, we find that the lysogenic state has lower entropy than lytic state, which proves that the lysogenic state has a higher biological order.