The presence or absence of this layer is important both in the biology of the bacterium and as a diagnostic tool. Both of these structures are continuous with the plasma membrane. Some bacteria have flagella. However, when present, bacterial flagella have no microtubules. Some have filamentous structures, pili , projecting from the surface.
Metabolic diversity is much greater than for other life forms.
In contrast, a eukaryote cell is uni- or multicellular and generally larger than a prokaryote cell. Membranous organelles including a nuclear envelope are present. The eukaryote ribosome is large and comprised of two subunits. Cell walls, present in some forms, are composed of cellulose . When present, flagella contain microtubules.