Re: Article: Is the Term 'Prokaryote' Obsolete?


"Robert Karl Stonjek" <rstonjek@xxxxxxxxxxxxxx> wrote in message news:e5kkbl$1215$1@xxxxxxxxxxxxxxxxxxxxxx
Is the Term 'Prokaryote' Obsolete?

The following points are made by Norman R. Pace (Nature 2006 441:289):

[snip Pace's points]

Full Text at ScienceWeek
http://scienceweek.com/2006/sw060602-1.htm

I couldn't find anything in the text summary by ScienceWeek that provides
an argument for a 'yes' answer to the title question.

Certainly, if 'prokaryote' is interpreted to mean 'pre-nucleus' then the
name is a mistake. One should never name a group of organisms to claim
that it represents something primitive. Naming in this way confuses the
role of definition and hypothesis. But this is a common sin among early-life
researchers (Woese's 'archaea', Lake's 'eocytes')

Once you get past the etymology, I think that 'prokaryote' is a perfectly
useful word denoting cells without nuclei. For example, here is a paper
suggesting that prokaryotes arose (on several occasions) from eukaryotes.
The still need the word without the connotations to express the hypothesis!

Poole A, Jeffares D, Penny D
Early evolution: prokaryotes, the new kids on the block.
Bioessays. 1999 Oct;21(10):880-9. Review.

Abstract:
Prokaryotes are generally assumed to be the oldest existing form of
life on earth. This assumption, however, makes it difficult to
understand certain aspects of the transition from earlier stages in
the origin of life to more complex ones, and it does not account for
many apparently ancient features in the eukaryotes. From a model of
the RNA world, based on relic RNA species in modern organisms, one can
infer that there was an absolute requirement for a high-accuracy RNA
replicase even before proteins evolved. In addition, we argue here that
the ribosome (together with the RNAs involved in its assembly) is so
large that it must have had a prior function before protein synthesis.
A model that connects and equates these two requirements (high-accuracy
RNA replicase and prior function of the ribosome) can explain many steps
in the origin of life while accounting for the observation that eukaryotes
have retained more vestiges of the RNA world. The later derivation of
prokaryote RNA metabolism and genome structure can be accounted for by
the two complementary mechanisms of r-selection and thermoreduction.

I don't think it is a good idea to reform technical terminology so as to
become compatible with the latest generally accepted hypotheses. The word
'prokaryote' was a mistake, but we are stuck with it now. It does little
harm if you can get past the connotations (as Poole et al did).


.

Relevant Pages

  • Paper: On the Evolution of the Standard Genetic Code - Vestiges of Critical Scale Invariance fro
    ... Invariance from the RNA World in Current Prokaryote Genomes ... consists of all codons of the type RNY (purine-any ...
    (sci.bio.evolution)
  • Article: A Simpler Origin for Life
    ... A Simpler Origin for Life ... The sudden appearance of a large self-copying molecule such as RNA was ... reported that, immediately after they had uncovered the structure of DNA, ... When RNA Ruled the World ...
    (sci.bio.evolution)
  • Re: Ancient RNA
    ... the common ancestor*S* of today's species and pseudo-species, ... life, maybe only a few thousand, with tens of thousands of *other* ... which suggest that the last universal ancestor was either an RNA ... generation, with non-RNA mutations usually being fatal, but RNA ...
    (talk.origins)
  • Re: Re: Whats the Problem?
    ... what is the process and what is the scientific evidence showing ... Can anyone identify the process by which the precursors to the DNA ... Life many have taken 10 million times as long, ... RNA instead of DNA. ...
    (talk.origins)
  • The French Version of OOL
    ... scrutiny in â??From Suns to Life: A Chronological Approach to the History of Life on ... Energy sources are also required and there ... forcing mission on inert chemicals. ... self-replicating peptides and the RNA world. ...
    (sci.bio.evolution)
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