However, certain groups of prokaryotes turned out do differ profoundly from the rest. We now recognize that the Archea are taxonomically as different from Bacteria as either are from eukaryotes, which collectively are called Eukarya . Archaeal walls differ widely, and are made from different materials. Walls of methanogens often contain pseudopeptidoglycan, similar to peptidoglycan, but with slightly different sugars and archictecture. Other archaea use polysaccharides, proteins, or glycoproteins as wall materials.
Many eukaryotes have cell walls.
These are built of a variety of materials, but never peptidoglycan. In Archaea, membranes are built from different types of lipids, polymers of the highly unsaturated molecule isoprene. These lipids are linked by ether bonds, not ester bonds. Structure of RNA Polymerase RNA polymerase is a crucial enzyme required for the synthesis of new RNA molecules. In bacteria, there is a single type of this enzyme, and it is built of four subunits.