Chapter 2 Steps of Realization of Genetic Information in Early Development

Abstract

Publisher Summary One of the most important problems pertaining to the mechanisms of development is to find out the events that take place between the time a gene comes into operation and its phenotypic expression. In the cells of the adult organism, regulation is predominant; in cell differentiation, a program prevails. The maintenance of the constant rate of translation or enzymatic activity is realized by the mechanisms of regulation, but the regular changes in the transcription pattern or those in the rate of protein synthesis in the course of development are carried out in accordance with a program. The mechanisms ensuring the regulation and programming are, evidently, basically different, as a regulatory apparatus must respond to a systems deviation from a given parameter, whereas the program implies alteration of the parameters in time. A programming unit should, therefore, include a time-meter, for example, an indicator of distance on the road or of developmental stage in the embryo. The mechanisms of realization of the regulation and of the program, however, may be similar: a turn of the wheel in the car or a change in the number of active ribosomes in the course of protein synthesis.