Firn RD and Jones CG (2009)
A Darwinian view of metabolism: molecular properties determines fitness
Journal of Experimental Botany, A Darwinian view of metabolism: molecular properties determine fitness J. Exp. Bot. 2009 60: 719-726; doi:10.1093/jxb/erp002. http://jxb.oxfordjournals.org/cgi/content/abstract/60/3/719?etoc
“Nothing in biology makes sense except in the light of evolution” (Theodosius Dobzhansky).
Why do organisms make the types of chemicals that they do? Evolutionary theory tells us that in populations individuals will be subject to mutations and some of those mutations will alter the enzymic capability of the individual to give rise to variants that make new chemicals. A mutant making a novel (for that species) chemical will only survive in the population if the “cost” of making the new chemical is outweighed by the benefits that result from making it. The benefits, or disbenefits that a novel chemical X can bring to a cell are not linked the the simple existence of X in the cell but to one of the multiple properties that X will possess due to its molecular structure. By considering only three basic types of physicochemical property, and by considering how selection pressures would differ for each kind of property, it is possible to account for much of the chemical diversity made by organisms. Furthermore, the evolutionary model explains why the properties of enzymes will differ depending on the molecular properties of the chemicals they are making and why the widely accepted terms “primary metabolism” and “secondary metabolism” have been so misleading and unsatisfactory.