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Archaea and bacteria have generally similar cell structure, but cell composition and organization set the archaea apart. Like bacteria, archaea lack interior membranes and organelles . [ 68 ] Like bacteria, the cell membranes of archaea are usually bounded by a cell wall and they swim using one or more flagella . [ 119 ]
Nick Lane and coauthors state that "The advantages and disadvantages of incorporating isoprenoids into cell membranes in different microenvironments may have driven membrane divergence, with the later biosynthesis of phospholipids giving rise to the unique G1P and G3P headgroups of archaea and bacteria respectively.
The cell wall is composed of pseudopeptidoglycan (and not peptidoglycan as in bacteria) which makes archaea resistant to lysozyme and many antibiotics that interfere with cell wall synthesis. The cell membrane consists of a lipid bilayer or monolayer, the backbone of which is composed of isoprene units that are linked to glycerol by ether bonds.
The cell envelope is composed of the cell membrane and the cell wall. As in other organisms, the bacterial cell wall provides structural integrity to the cell. In prokaryotes , the primary function of the cell wall is to protect the cell from internal turgor pressure caused by the much higher concentrations of proteins and other molecules ...
These microbes are prokaryotes, meaning they have no cell nucleus or any other membrane-bound organelles in their cells. Archaea were initially classified as bacteria, but this classification is outdated. [93] Archaeal cells have unique properties separating them from the other two domains of life, Bacteria and Eukaryota.
The cell membrane of archaea consist mostly of ether phospholipids. These lipids have a flipped chirality compared to bacterial and eukaryotic membranes, a conundrum known as the "lipid divide". The "tail" groups are also not simply n-alkyl groups, but highly methylated chains made up of saturated isoprenoid units (e.g. phytanyl). [15]
The archaellum (pl.: archaella; formerly archaeal flagellum) is a unique structure on the cell surface of many archaea that allows for swimming motility. The archaellum consists of a rigid helical filament that is attached to the cell membrane by a molecular motor. This molecular motor – composed of cytosolic, membrane, and pseudo-periplasmic ...
The cellular components of prokaryotes are not enclosed in membranes within the cytoplasm, like eukaryotic organelles.Bacteria have microcompartments, quasi-organelles enclosed in protein shells such as encapsulin protein cages, [4] [5] while both bacteria and some archaea have gas vesicles.