Next installment from the pseudo-scientists, or is it a case of the truth hurting?
were recognized as a unique domain of life based on the sequence comparisons of
ribosomal RNA (rRNA) of various organisms by Woese and colleagues. 1
Archaea differ from the other two domains of
life—bacteria and eukarya —not only in their archaea-specific signatures in
certain regions of rRNAs, but also in their cell membranes, which are composed
of lipids made of ether, unlike bacteria or eukarya whose membrane lipids are made
of ester. 2
fact, as stated by Woese and colleagues, “for every well characterized
molecular system there exists a characteristic eubacterial, archaebacterial,
and eukaryotic version”. 3
Archaea are similar to bacteria in many
aspects. Like bacteria, archaea do not have nuclei, and are thus prokaryotes.
Archaea also lack other membrane-bound organelles, including mitochondria and
chloroplasts. Archaeal genomes are small and circular like those of bacteria.
No spliceosomal introns have been found in archaea. Like bacteria, archaea also
lack the machinery to synthesize eukaryotic telomeres and to splice
spliceosomal introns, two processes essential for the survival of eukaryotes.
This shortage of higher level eukaryotic complexity does not hurt archaea in
any way because they have no need of these systems. However, the lack of these
systems, including any transitional forms for them, creates an unbridgeable
chasm between prokaryotes and eukaryotes in the grand evolutionary paradigm. 4
Woese, C. R., and G. E. Fox. 1977. Phylogenetic structure of the prokaryotic
domain: The primary kingdoms. Proceedings of the National
Academy Sciences USA 74,
Gutell, R. R., B. Weiser, C. R. Woese, and H. F. Noller. 1985. Comparative
anatomy of 16-S-like ribosomal RNA. Progress in Nucleic Acid Research and
Molecular Biology 32:155–216.
Woese, C. R., O. Kandler, and M. L. Wheelis. 1990. Towards a natural system of
organisms: proposal for the domains Archaea, Bacteria, and Eucarya. Proceedings
of the National Academy
Sciences USA 87,
4. “Information Processing Differences
Between Archaea and Eukarya—Implications for Homologs and the Myth of
Eukaryogenesis,” by C. L. Tan and J. P. Tomkins.