Strategies of Genetic Regulation in Prokaryotes
One of the most striking characteristics of living systems is that they function in an orderly manner despite their high degree of complexity. One workable definition of regulation, in fact, is the set of mechanisms that allows organisms to maintain this orderly functioning. It is important to realize, however, that regulation was not superimposed upon living systems; orderly processes are simply more successful than are disorderly ones, and therefore tend to be preserved through the evolutionary process by conferring advantages upon organisms that possess them. The thousands of chemical reactions occurring in cells are controlled by regulatory mechanisms that operate at many different levels. This introductory chapter focuses on those that operate at the level of gene expression and will introduce some of the strategies of genetic regulation that have evolved in prokaryotic organisms. Scanning the table of contents of this brief essay should suffice to tell the reader that a very general overview is in store for him. The renaissance in biological research that occurred in the last 25 years has been due mostly to the exciting studies concerning genetic regulation in prokaryotes. I have tried to abstract from those studies the most important basic principles they illustrate and to organize into a few generalizations the enormous body of data they have produced. I believe it is these principles and generalizations with which the reader will need to arm himself before proceeding further into this volume. It is to be hoped that the necessarily simplistic view of regulation they provide will be preferable to the bewilderment that so often results from exhaustive reviews that include the details of many specific regulated systems.
KeywordsCatabolite Repression Inducible System Stringent Response Polycistronic mRNA Repressible System
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