The discovery of " T . celer " turned the position of the archaebacterial phylogenetic tree . " T . celer " was discovered to share a closer phylogenetic relationship with methanogenic archaebacteria, as opposed its phenotypic analogue, extremely thermophilic archaebacteria.
42.
Glycerophospholipids may be subdivided into distinct classes, based on the nature of the polar headgroup at the " sn "-3 position of the glycerol backbone in eukaryotes and eubacteria, or the " sn "-1 position in the case of archaebacteria.
43.
However, molecular systematics showed prokaryotic life to consist of two separate domains, originally called " Eubacteria " and " Archaebacteria ", but now called " Bacteria " and " Archaea " that evolved independently from an ancient common ancestor.
44.
"' Domain Archaea "' prokaryotic, no nuclear membrane, distinct biochemistry and RNA markers from bacteria, possess unique ancient evolutionary history for which they are considered some of the oldest species of organisms on Earth; traditionally classified as archaebacteria; often characterized by living in extreme environments.
45.
By 1977, Woese and George Fox announced that some bacteria, such as methanogens, lacked the rRNA units that Woese's phylogenetic studies were based on; they argued that these organisms were actually distinct enough from conventional bacteria and the so-called higher organisms to form their own kingdom, which they called archaebacteria.
46.
"What this enormous enterprise has shown, however, is that Archaebacteria are not really very different from " E . coli " in the organization of their genes ( e . g . operons ) and genomes, or their replication, transcription and translation machinery, as Keeling, Charlebois & Doolittle ( 1994 ) have clearly accepted.
47.
Thomas Cavalier-Smith thought at first, as it was nearly consensually admitted at that time, that the difference between " eubacteria " and " archaebacteria " was so great ( particularly considering the genetic distance of ribosomal genes ) that they needed to be separated into two different kingdoms, hence splitting the empire Bacteria into two kingdoms.
48.
The unity of cell machinery for inserting nascent proteins directly into membranes and of key membrane proteins shows that all cells are lineal, vertical descendants of the very first cell ( Cavalier-Smith 2001, 2006c ), notwithstanding the dramatic structural differences between bacteria and eukaryotes or the unique membrane lipid chemistry of archaebacteria which evolved from conventional bacteria ( eubacteria ) by lipid replacement, not independently from membrane-free naked-gene precursors as has sometimes been claimed.
49.
"[ . . . ] I felt obligated to go into this history in some detail because the very early ideas of Woese & Fox ( 1977a, b ) about the independent and early divergence of archaebacteria, eubacteria and eukaryotes from a progenote ( though not now accepted even by the authors themselves ), and the thoroughly mistaken criticism of the concept of bacteria, played a large role in determining the present views of many biologists on the status of archaebacteria [ . . . ]"
50.
"[ . . . ] I felt obligated to go into this history in some detail because the very early ideas of Woese & Fox ( 1977a, b ) about the independent and early divergence of archaebacteria, eubacteria and eukaryotes from a progenote ( though not now accepted even by the authors themselves ), and the thoroughly mistaken criticism of the concept of bacteria, played a large role in determining the present views of many biologists on the status of archaebacteria [ . . . ]"
