There are three domains of life, Eukarya, Eubacteria, and Archaebacteria, Eukarya is quite easy to distinguish as this comprises all organisms composed of eukaryotic cells, this, eukaryotic cells are characterized by the presence of a nucleus and several organelles. Eubacteria and Archaebacteria are both prokaryotes (there is no nucleus or organelles), their main differences lie in the cell membrane, meanwhile, bacteria have ester bonds in their phospholipids, archaea have ether bonds, also the phospholipid in archaea possess an isoprenoid chain with branching very different from the fatty acids of other organisms, finally, their enzyme machinery and metabolic route are significantly different than in other organisms.