Kinetics and biological problems

Atkins (1982, p. 921) makes an interesting distinction between chemical kinetics and the field of chemical dynamics of individual steps. The former is descriptive in terms of rate equations defining the number of intermediates and their rates of interconversion. The latter is in the realm of chemical physics, but it is becoming of interest as modem techniques help to describe the dynamic behaviour of macromolecules. A similar distinction was made above between the descriptive and the mechanistic role of kinetic studies on systems at a more complex level. This emphaazes the important point that general questions about the mechanism of a reaction or a functional process are open ended. It is essential that specific questions are asked and methods are used which are appropriate to their resolution. 

A warning is necessary concerning the use of mathematical models in biology. These must be closely linked to the design of experiments which can test them. Examples will come up in the text which demonstrate the danger of models taking over from reality. It is also important to realize that a biological system does not necessarily work at optimum efficiency. Just as in private enterprise, to succeed one only has to be the most efficient in one s immediate environment. 

The application of kinetic equations to biological problems on the largest scale is found in modelling of the behaviour of populations. The use of 

The Gompertz equation is often written in its modem form  

For this growth curve the term (K-N)IK in equation (1.2.4) is added as a feedback term to the equation for exponential growth dNIdt-bN. This provides an inverse linear dependence of growth on population density. 

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