Eukaryotes: prokaryote-eukaryote dichotomy

Sapp J (1994) Evolution by association a history of symbiosis. Oxford University Press, New York Sapp J (2002) Paul Buchner and hereditary symbiosis in insects. Int Microbiol 5 145-160 Sapp J (2003) Genesis the evolution of biology. Oxford University Press, New York Sapp J (2005a) The bacterium s place in nature. In Sapp J (ed) Microbial phylogeny and evolution concepts and controversies. Oxford University Press, New York, pp 1-52 Sapp J (2005b) The Prokaryote-eukaryote dichotomy meanings and mythology. Microbiol Mol Biol Rev 69 292-305... 

Woese surveys the field of battle in the Introduction to this volume. The war is clearly over, and we cannot return again to a simple prokaryote/eukaryote dichotomy of the kind drawn for us by Stanier and van Niel three decades ago. There may however be a deeper revolution ahead, one which challenges not our understanding of the relationships between evolutionary lineages but the very definition of lineage, and it is time for stock taking. 

Still more confusion plagued early researches, when it was not realized that the biosynthetic routes to thiamine in prokaryotes and eukaryotes are quite different, a fact not expected at the outset. Thus, evidence collected from the study of yeast could not be transposed to bacteria, and vice-versa. For instance, formate is a most efficient precursor of one of the carbon atoms of the pyrimidine part of thiamine (pyramine), both in yeasts and enterobacteria, but incorporates at C-2 in bacteria and at C-4 in yeast. However, as is briefly covered in Section VIII, this dichotomy of pathways might have a deep significance in the perspective of biochemical evolution during primitive life on Earth. 

The basic dichotomy between organisms of the present-day world is between prokaryote and eukaryotes. 

During the 1970s, the dichotomy of cells into prokaryotic and eukaryotic began to be challenged by the discovery of a few classes of bacteria, called archaebacteria, which, although possessing the general structural features of prokaryotic cells, exhibit distinctive biochemical characteristics. 

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