Chemical process development evolution

This kind of impact is complicated by the possible influence of these chemicals on the process of evolution itself When a chemical comes into widespread use, especially an insecticide, it is only a matter of time before the target insects develop resistance. That is, those individual insects with natural resistance (as a result of natural variation and mutation) survive successive assaults of a given chemical and reproduce broods with similar immunity, which come to be common in the whole population. In a short period of time (because insects reproduce quickly), the species becomes resistant altogether (Table 4.6). ... 

The search for RNAs with new catalytic functions has been aided by the development of a method that rapidly searches pools of random polymers of RNA and extracts those with particular activities SELEX is nothing less than accelerated evolution in a test tube (Box 26-3). It has been used to generate RNA molecules that bind to amino acids, organic dyes, nucleotides, cyano-cobalamin, and other molecules. Researchers have isolated ribozymes that catalyze ester and amide bond formation, Sn2 reactions, metallation of (addition of metal ions to) porphyrins, and carbon-carbon bond formation. The evolution of enzymatic cofactors with nucleotide handles that facilitate their binding to ribozymes might have further expanded the repertoire of chemical processes available to primitive metabolic systems. 

It is likely that future developments will address the automation of in vitro evolution technologies, as chemical processes are in general easier... 

Up to this point, we have a reasonable interpretation of definite evidence, beyond this, imagination must come into play. It is fair to assume that the process of evolution was extremely slow, and that each element was developed gradually and passed from an unfinished to a finished stage. The chemical atoms are now known to be extremely complex structures, each with an electropositive nucleus surrounded by electrons in rapid motion. That such a structure could have been developed instantaneously, with no previous preparation, is hardly probable, for the process was one of condensation, from lighter to heavier, and that, it would seem, must have acquired time. The process was one from relative simplicity of structure to relative complexity, and with the maximum condensation, as shown by uranium and thorium, a minimum of stability was reached. That is, so far as we now know for less Stable atoms may have been formed, to exist for a brief period and then vanish. Some of the radioactive elements which appear as products of the decay of uranium are of this kind. On that theme, more later. 

At this early development stage, there is often very little time available to study why the chemical reaction process works or what makes it fail. The process developer confirms the operability and adjusts the laboratory process as necessary. For example, are the reaction times and volumes necessary, are there better solvents, are reagent ratios appropriate, what are the gas and heat evolution rates, is mixing or solubility going to be a problem, can reasonable yield and impurity levels be achieved At this stage, information about scalability may rest solely on reproducibility at a certain laboratory scale. Fortunately, scale up in the pilot plant under careful control and under the watchful eyes of the process developer usually results in successful production of larger quantities of material... 

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