In addition, most have a bacterial cell wall consisting mostly of peptidoglycan and an outermost layer called a capsule . Some bacteria possess an additional lipopolysaccharide outermost layer and are said to be gram negative. 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.