All organisms that do not posses a membrane-bound nucleus, including the Schizomycetes, or bacteria, the Cyanophyta, or blue-green algae, and the Prochlorophyta, are classified as belonging to the Kingdom Monera, and are referred to as being prokaryotic (meaning "having a primitive nucleus"). In addition to lacking a nuclear membrane, prokaryotic cells do not possess most of the other membrane-bound structures found in eukaryotic cells, or those cells that have a true nucleus. Prokaryotic cells lack endoplasmic reticulum, Golgi apparatus, and lysosomes. They also lack mitochondria although the inner surface of the prokaryotic cell membrane carries out a similar ATP-producing function.
Prokaryotic organisms that are photosynthetic do have chlorophyll-containing vesicles, or lamellae, but do not possess chloroplasts which, in plants, contain the lamellae. Some prokaryotic cells have cell walls, like plant cells do, but prokaryotic cell walls are made from murein, an amino-acid-embedded polysaccharide, instead of from cellulose. Finally, prokaryotic cells do not have microtubules. As a result, prokaryotic cells' flagella have a radically different structure from the flagella of eukaryotic cells. Formed by a complicated assembly of rings, rods, a hook, and a filament, a prokaryotic flagellum produces a rotary motion instead of a whip-like one as a eukaryotic flagellum does. Nor are prokaryotic flagella encapsulated by cell membrane as eukaryotic flagella are.
Although prokaryotic cells do not have a nuclear membrane, prokaryotic cells do
