Archaebacteria but instead was a chimera formed by fusion and integration of the genomes of an archaebacterium and a gram-negative bacterium. The available data indicate that the primary fusion event that gave rise to the ancestral eukaryotic cell was unique and that it was very probably distinct from (and preceded) the one that gave rise to mitochondria and hydrogenosomes. These results provide e
Distinction within prokaryotes, formingthe primary taxonomic division within them, which is supported by both molecular sequence data and morphological features, is of the monoderm prokaryotes (Monodermata, i.e., those bounded by a single cell membrane) and the diderm prokaryotes (Didermata, i.e., those bounded by inner and outer cell membranes defining a periplasmic compartment). In that sense, b