Karyotic cell nucleus and endomembrane system as per the chimeric model. The key event in the origin of the eukaryotic cell is postulated to be a symbiotic association between a gram-negative eubacterium (from the proteobacteria-1 group) and likely an "eocyte" archaebacterium. This association led to the loss of the outer membrane from the gram-negative bacterium (not shown). As the membrane of th
E signature sequences in different proteins support the division of Archaebacteria into two distinct groups (Euryarchaeota and Crenarchaeota) and of gram-positive bacteria into at least two groups, corresponding to the low-G C and high-G C species, of which the high-G C group is specifically related to the diderm prokaryotes. The DeinococcusThermus group of species appears to be intermediate in th
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