The meaning of the term prokaryote is critically analyzed. The conclusion reached is that this term does not have a real biological sense, above all because we are not able to link to this term a specific biological characteristic, i.e. the hypothetical evolutionary stage of the prokaryote would seem to have been unable to result in a completed cell, which could possibly be due to the recapitulation of the fundamental characteristics that might have been common to bacteria and archaea. This would define a biological immaturity of this evolutionary stage because otherwise we would have found traits already clearly defined at this level of cellular evolution. Therefore, the lack of well-defined traits characterising the prokaryote would seem to imply an evolutionary stage still in rapid evolution, i.e. with a tempo and a mode of evolution typical of a progenote. This in turn would seem to imply that the last universal common ancestor (LUCA) has been a progenote at least when the domains of life are only two—the bacterial and archaeal domains—because, in this case, the LUCA’s node should coincide with that of prokaryote on the tree of life. Instead, if the root of the tree of life would be placed in the bacterial domain or in the archaeal one, we might again, very likely, have a LUCA with a character of progenote being, under these conditions, the LUCA a prokaryote-like organism.
Progenote LUCA Evolutionary stages Protocell
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Becerra A, Delaye L, Islas S, Lazcano A (2007) The very early stages of biological evolution and the nature of the last universal common ancestor of the three major cell domains. Annu Rev Ecol Evol Syst 8:361–379CrossRefGoogle Scholar
Delaye L, Becerra A, Lazcano A (2002) The nature of the last common ancestor. In: de Pouplana LR (ed) The genetic code and the origin of life. Landes Bioscience, GeorgetownGoogle Scholar
Delaye L, Becerra A, Lazcano A (2005) The universal common ancestor: what’s in a name? Orig Life Evol Biosph 35:537–554PubMedCrossRefGoogle Scholar
Di Giulio M (2001) The non-universality of the genetic code: the universal ancestor was a progenote. J Theor Biol 209:345–349PubMedCrossRefGoogle Scholar
Di Giulio M (2011) The Last Universal Common Ancestor (LUCA) and the Ancestors of Archaea and Bacteria were Progenotes. J Mol Evol 72:119–126PubMedCrossRefGoogle Scholar
Spieth J, Brooke G, Kuersten S, Lea K, Blumenthal T (1993) Operons in C. elegans: polycistronic mRNA precursors are processed by trans-splicing of SL2 to downstream coding regions. Cell 73:521–532PubMedCrossRefGoogle Scholar
Woese CR, Kandler O, Wheelis ML (1990) Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eukarya. Proc Natl Acad Sci USA 87:4576–4579PubMedCentralPubMedCrossRefGoogle Scholar