The metabolism of carbohydrates, lipids, nucleic acids and proteins, but we have already underlined the fact that this division is rather arbitrary; it is justified mainly because it facilitates the presentation. In fact — as observed repeatedly — inter-relations between various types of compounds are numerous and the entire cellular metabolism must be regarded as a set of harmoniously integrated [...]
The effects of variations of substrate concentration on the velocity of an enzymatic reaction. We may only add that in some cases, variations of substrate or co-substrate concentration [S] can exert important effects on the metabolism by permitting either the synthesis, or on the contrary the degradation of a substance X, or by determining the metabolic pathway in which a [...]
Pluricellular organisms are characterized by the existence of tissues, i.e. sets of cells which have acquired specialized functions. This specialization is advantageous in the sense that it permits a distribution of work but it necessitates means of controlling and integrating the activities of various tissues. Hormones constitute precisely a means of communication between territories distant from one another. It was [...]