It’s time retire the prokaryote

Prokaryotes What is a prokaryote? Does anyone really know? In this article from Microbiology Today Norman Pace says not, and believes that the term has stuck since it was first coined in the late 19th century, but with no scientific foundation. He would like all microbiologists to join him in scrapping this anachronism in modern biology:

Experimental results rarely upset the common wisdom of a scientific discipline, but that happened to biology late in the 20th century. The common wisdom in deep evolution and how we classify organisms was rendered sorely in need of modernization. And that modern-ization is happening too slowly. The anachronism here is the notion of “prokaryote” and the model of biological organization and evolution that it elicits. This model, which I term the “prokaryote–eukaryote” model, posits that fundamentally there are two kinds of organisms, prokaryotes and eukaryotes, defined by the presence or absence of a nucleus (more properly nuclear membrane). Additionally, the model proposes that prokaryotes gave rise to eukaryotes, as shown in the figure overleaf. The problem, however, is that the prokaryote concept has been undermined critically by sequence-based phylogenetic results. Indeed, the notion of prokaryote was scientifically illogical from the beginning because the definition, an “organism without a nucleus”, is a negative definition. No-one can tell you what a prokaryote is, they can only tell you what it is not. Yet, institutional biology embraced the notion of prokaryote and it came to dominate textbooks, journals and discourse in matters of deep evolution. But the hypothesis of the prokaryote was never tested…

Pace, N.R. Microbiology Today, May 2009, p85-87.


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One Response to It’s time retire the prokaryote

  1. In my opinion words are tools. They only died when they are useless or because we found an alternative word that is better to define or describe things.

    In the case of Norman Pace’s article I do not see any of those points. To discard “prokaryote” because is a negative definition is like the proposition to discard “sessile” because its meaning is “non-movil” . In fact, the prefix “pro-” means “before the”, so “prokaryot” means “before the nucleus” and not “whitout nucleus”, although is the last acception the one that we use nowadays.

    And what about the alternatives? As a professor I always say to my alumni that there are three domains, but when we go down to explain the cellular architecture it is easy to see that the main diference between Eukarya, Bacteria and Archaea is that the first has nucleus and the other two, don’t have (except Gemmata globioscurus). So, do we describe cellular architecture of Bacteria and Archaea as “non-eukariotic” instead of “prokariotic”?

    Last thing, for the moment, all the current hypothesis about the progenote describes it with a “prokaryote organization”. The nucleus came later in evolution.

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