"The first edition of A Genetic Switch has become a classic exposition of gene regulation, explaining in simple molecular terms how proteins bind DNA and turn genes on and off as the virus lambda grows in bacteria. To that original text, reprinted here with small modifications, the author has added a chapter describing recent advances that extend and deepen our understanding of lambda's "genetic switch." The study of lambda reveals the basic reactions that underlie transcriptional regulation in all organisms and shows how those reactions can be combined to produce a complex regulatory circuit."--BOOK JACKET.