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<title>Cell envelope</title>

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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Cell envelope</span></span>

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<p>The <b>cell envelope</b> comprises the inner <a href="Cell_membrane" title="Cell membrane">cell membrane</a> and the <a href="Cell_wall" title="Cell wall">cell wall</a> of a <a href="Bacterium" class="mw-redirect" title="Bacterium">bacterium</a>. In <a href="Gram-negative_bacteria" title="Gram-negative bacteria">Gram-negative bacteria</a> an <a href="Bacterial_outer_membrane" title="Bacterial outer membrane">outer membrane</a> is also included.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> This envelope is not present in the <a href="Mollicutes" title="Mollicutes">Mollicutes</a> where the cell wall is absent.

</p><p>Bacterial cell envelopes fall into two major categories: a <a href="Gram-positive" class="mw-redirect" title="Gram-positive">Gram-positive</a> type which stains purple during <a href="Gram_staining" class="mw-redirect" title="Gram staining">Gram staining</a> and a Gram-negative type which stains pink during Gram staining. Either type may have an enclosing <a href="Bacterial_capsule" title="Bacterial capsule">capsule</a> of <a href="Polysaccharides" class="mw-redirect" title="Polysaccharides">polysaccharides</a> for extra protection. As a group these are known as <a href="Polysaccharide_encapsulated_bacteria" class="mw-redirect" title="Polysaccharide encapsulated bacteria">polysaccharide encapsulated bacteria</a>.

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<div class="mw-heading mw-heading2"><h2 id="Function">Function</h2></div>

<p>As in other organisms, the bacterial <a href="Cell_wall" title="Cell wall">cell wall</a> provides structural integrity to the cell. In <a href="Prokaryotes" class="mw-redirect" title="Prokaryotes">prokaryotes</a>, the primary function of the cell wall is to protect the cell from internal <a href="Turgor_pressure" title="Turgor pressure">turgor pressure</a> caused by the much higher concentrations of proteins and other molecules inside the cell compared to its external environment. The bacterial cell wall differs from that of all other organisms by the presence of <a href="Peptidoglycan" title="Peptidoglycan">peptidoglycan</a> (poly-<i>N</i>-acetylglucosamine and <i>N</i>-acetylmuramic acid), which is located immediately outside of the <a href="Cytoplasmic_membrane" class="mw-redirect" title="Cytoplasmic membrane">cytoplasmic membrane</a>. <a href="Peptidoglycan" title="Peptidoglycan">Peptidoglycan</a> is responsible for the rigidity of the bacterial cell wall and for the determination of cell shape. It is relatively porous and is not considered to be a permeability barrier for small substrates. While all bacterial cell walls (with a few exceptions e.g. intracellular parasites such as <i><a href="Mycoplasma" title="Mycoplasma">Mycoplasma</a></i>) contain peptidoglycan, not all cell walls have the same overall structures. This is notably expressed through the classification into Gram-positive and Gram-negative bacteria.

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<div class="mw-heading mw-heading2"><h2 id="Types">Types</h2></div>

<div class="mw-heading mw-heading3"><h3 id="The_Gram-positive_cell_wall">The Gram-positive cell wall</h3></div>

<p>The <a href="Gram-positive_cell_wall" class="mw-redirect" title="Gram-positive cell wall">Gram-positive cell wall</a> is characterized by the presence of a very thick peptidoglycan layer, which is responsible for the retention of the crystal violet dyes during the <a href="Gram_staining" class="mw-redirect" title="Gram staining">Gram staining</a> procedure. It is found exclusively in organisms belonging to the <a href="Actinomycetota" title="Actinomycetota">Actinomycetota</a> (or high %G+C Gram-positive organisms) and the <a href="Bacillota" title="Bacillota">Bacillota</a> (or low %G+C Gram-positive organisms). Bacteria within the <a href="Deinococcota" title="Deinococcota">Deinococcota</a> group may also exhibit Gram-positive staining behavior but contain some cell wall structures typical of Gram-negative organisms. Imbedded in the Gram-positive cell wall are polyalcohols called <a href="Teichoic_acid" title="Teichoic acid">teichoic acids</a>, some of which are lipid-linked to form <a href="Lipoteichoic_acid" title="Lipoteichoic acid">lipoteichoic acids</a>. Because lipoteichoic acids are covalently linked to lipids within the <a href="Cytoplasmic_membrane" class="mw-redirect" title="Cytoplasmic membrane">cytoplasmic membrane</a> they are responsible for linking the <a href="Peptidoglycan" title="Peptidoglycan">peptidoglycan</a> to the <a href="Cytoplasmic_membrane" class="mw-redirect" title="Cytoplasmic membrane">cytoplasmic membrane</a>. Teichoic acids give the gram-positive cell wall an overall negative charge due to the presence of <a href="Phosphodiester_bonds" class="mw-redirect" title="Phosphodiester bonds">phosphodiester bonds</a> between teichoic acid monomers.

</p><p>Outside the cell wall, many Gram-positive bacteria have an <a href="S-layer" title="S-layer">S-layer</a> of "tiled" proteins. The S-layer assists attachment and biofilm formation. Outside the S-layer, there is often a <a href="Capsule_(microbiology)" class="mw-redirect" title="Capsule (microbiology)">capsule</a> of polysaccharides. The capsule helps the bacterium evade host <a href="Phagocytosis" title="Phagocytosis">phagocytosis</a>. In laboratory culture, the S-layer and capsule are often lost by reductive evolution (the loss of a trait in absence of positive selection).

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<div class="mw-heading mw-heading3"><h3 id="The_Gram-negative_cell_wall">The Gram-negative cell wall</h3></div>

<p>The <a href="Gram-negative_cell_wall" class="mw-redirect" title="Gram-negative cell wall">Gram-negative cell wall</a> contains a thinner <a href="Peptidoglycan" title="Peptidoglycan">peptidoglycan</a> layer adjacent to the <a href="Cytoplasmic_membrane" class="mw-redirect" title="Cytoplasmic membrane">cytoplasmic membrane</a> than the Gram-positive wall, which is responsible for the cell wall's inability to retain the crystal violet stain upon decolourisation with ethanol during <a href="Gram_staining" class="mw-redirect" title="Gram staining">Gram staining</a>. In addition to the <a href="Peptidoglycan" title="Peptidoglycan">peptidoglycan</a> layer the Gram-negative cell wall also contains an additional outer membrane composed by <a href="Phospholipid" title="Phospholipid">phospholipids</a> and <a href="Lipopolysaccharide" title="Lipopolysaccharide">lipopolysaccharides</a> which face into the external environment. The highly charged nature of <a href="Lipopolysaccharide" title="Lipopolysaccharide">lipopolysaccharides</a> confer an overall negative charge to the Gram -negative cell wall. The chemical structure of the outer membrane <a href="Lipopolysaccharide" title="Lipopolysaccharide">lipopolysaccharides</a> is often unique to specific bacterial strains (i.e. sub-species) and is responsible for many of the <a href="Antigen" title="Antigen">antigenic</a> properties of these strains.

</p><p>As a <a href="Phospholipid_bilayer" class="mw-redirect" title="Phospholipid bilayer">phospholipid bilayer</a>, the lipid portion of the outer membrane is largely impermeable to all charged molecules. However, channels called <a href="Porin_(protein)" title="Porin (protein)">porins</a> are present in the outer membrane that allow for <a href="Passive_transport" title="Passive transport">passive transport</a> of many <a href="Ion" title="Ion">ions</a>, <a href="Sugar" title="Sugar">sugars</a> and <a href="Amino_acid" title="Amino acid">amino acids</a> across the outer membrane. These molecules are therefore present in the <a href="Periplasm" title="Periplasm">periplasm</a>, the region between the plasma membrane and outer membrane. The <a href="Periplasm" title="Periplasm">periplasm</a> contains the peptidoglycan layer and many proteins responsible for substrate binding or <a href="Hydrolysis" title="Hydrolysis">hydrolysis</a> and reception of extracellular signals. The periplasm is thought to exist as a gel-like state rather than a liquid due to the high concentration of proteins and <a href="Peptidoglycan" title="Peptidoglycan">peptidoglycan</a> found within it. Because of its location between the cytoplasmic and outer membranes, signals received and substrates bound are available to be transported across the <a href="Cytoplasmic_membrane" class="mw-redirect" title="Cytoplasmic membrane">cytoplasmic membrane</a> using transport and signaling proteins imbedded there.

</p><p>In nature, many uncultivated Gram-negative bacteria also have an <a href="S-layer" title="S-layer">S-layer</a> and a <a href="Capsule_(microbiology)" class="mw-redirect" title="Capsule (microbiology)">capsule</a>. These structures are often lost during laboratory cultivation.

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<div class="mw-heading mw-heading3"><h3 id="Mycobacteria">Mycobacteria</h3></div>

<p>The <i><a href="Mycobacteria" class="mw-redirect" title="Mycobacteria">Mycobacteria</a></i> (<a href="Acid-fast" class="mw-redirect" title="Acid-fast">acid-fast</a> bacteria) have a cell envelope which is not typical of Gram-positives or Gram-negatives. The mycobacterial cell envelope does not consist of the outer membrane characteristic of Gram-negatives, but has a significant peptidoglycan-arabinogalactan-mycolic acid wall structure which provides an external permeability barrier. Therefore, there is thought to be a distinct 'pseudoperiplasm' compartment between the cytoplasmic membrane and this outer barrier. The nature of this compartment is not well understood.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> <a href="Acid-fast" class="mw-redirect" title="Acid-fast">Acid-fast bacteria</a>, like <i><a href="Mycobacteria" class="mw-redirect" title="Mycobacteria">Mycobacteria</a></i>, are resistant to decolorization by acids during staining procedures. The high <a href="Mycolic_acid" title="Mycolic acid">mycolic acid</a> content of <i>Mycobacteria</i>, is responsible for the staining pattern of poor absorption followed by high retention. The most common staining technique used to identify acid-fast bacteria is the <a href="Ziehl%E2%80%93Neelsen_stain" title="Ziehl–Neelsen stain">Ziehl–Neelsen stain</a> or acid-fast stain, in which the acid fast bacilli are stained bright red and stand out clearly against a blue background.

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<div class="mw-heading mw-heading3"><h3 id="Bacteria_lacking_a_peptidoglycan_cell_wall">Bacteria lacking a peptidoglycan cell wall</h3></div>

<p>The obligate intracellular bacteria in the family <a href="Chlamydiaceae" title="Chlamydiaceae">Chlamydiaceae</a> are unique in their morphology as they do not contain detectable amounts of peptidoglycan in the cell wall of their infectious forms.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> Instead, the extracellular forms of these Gram-negative bacteria maintain their structural integrity by relying on a layer of disulfide bond cross-linked cysteine-rich proteins, which is located between cytoplasmic membrane and outer membrane in a manner analogous to the peptidoglycan layer in other Gram-negative bacteria.<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> In the intracellular forms of the bacterium the disulfide cross linkage is not found, which confers this form more mechanically fragile.

</p><p>The cell envelopes of the bacterial class of <a href="Mollicute" class="mw-redirect" title="Mollicute">mollicutes</a> do not have a cell wall.<sup id="cite_ref-Rottem_2003_5-0" class="reference"><a href="#cite_note-Rottem_2003-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> The main <a href="Pathogenic_bacteria" title="Pathogenic bacteria">pathogenic bacteria</a> in this class are <a href="Mycoplasma" title="Mycoplasma">mycoplasma</a> and <a href="Ureaplasma" title="Ureaplasma">ureaplasma</a>.<sup id="cite_ref-Rottem_2003_5-1" class="reference"><a href="#cite_note-Rottem_2003-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup>

</p><p><a href="L-form_bacteria" title="L-form bacteria">L-form bacteria</a> are strains bacteria that lack cell walls derived from bacteria that normally possess cell walls.<sup id="cite_ref-pmid19212404_6-0" class="reference"><a href="#cite_note-pmid19212404-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup>

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<ul><li><a href="Viral_envelope" title="Viral envelope">Viral envelope</a></li></ul>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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<li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20090628224336/http://www.mercksource.com/pp/us/cns/cns_hl_dorlands_split.jsp?pg=/ppdocs/us/common/dorlands/dorland/three/000035855.htm">"envelope"</a> at <i><a href="Dorland's_medical_reference_works" title="Dorland's medical reference works">Dorland's Medical Dictionary</a></i></span>

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<li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text">IC Sutcliffe, DJ Harrington.Lipoproteins of mycobacterium tuberculosis: an abundant and functionally diverse class of cell envelope components. FEMS Microbiology Reviews 28 (2004) 645-759</span>

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<li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text">Chopra I, Storey C, Falla TJ, Pearce JH. Antibiotics, peptidoglycan synthesis and genomics: the chlamydial anomaly revisited. Microbiology. 1998 144 ( Pt 10):2673-8.</span>

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<li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text">Hatch TP. Disulfide cross-linked envelope proteins: the functional equivalent of peptidoglycan in chlamydiae? J. Bacteriol. 1996 178:1–5.</span>

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</style><cite id="CITEREFRottem_S2003" class="citation journal cs1">Rottem S (April 2003). "Interaction of mycoplasmas with host cells". <i>Physiol. Rev</i>. <b>83</b> (2): <span class="nowrap">417–</span>32. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1152%2Fphysrev.00030.2002">10.1152/physrev.00030.2002</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/12663864">12663864</a>.</cite></span>

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<li id="cite_note-pmid19212404-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-pmid19212404_6-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFLeaverDomínguez-CuevasCoxheadDaniel2009" class="citation journal cs1">Leaver M, Domínguez-Cuevas P, Coxhead JM, Daniel RA, Errington J (February 2009). "Life without a wall or division machine in Bacillus subtilis". <i>Nature</i>. <b>457</b> (7231): <span class="nowrap">849–</span>53. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1038%2Fnature07742">10.1038/nature07742</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/19212404">19212404</a>.</cite></span>

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</style><div id="Structures_of_the_cell_/_organelles162" style="font-size:114%;margin:0 4em">Structures of the <a href="Cell_(biology)" title="Cell (biology)">cell</a> / <a href="Organelle" title="Organelle">organelles</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Endomembrane_system" title="Endomembrane system">Endomembrane <br>system</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Cell_membrane" title="Cell membrane">Cell membrane</a></li>

<li><a href="Cell_nucleus" title="Cell nucleus">Nucleus</a></li>

<li><a href="Endoplasmic_reticulum" title="Endoplasmic reticulum">Endoplasmic reticulum</a></li>

<li><a href="Golgi_apparatus" title="Golgi apparatus">Golgi apparatus</a></li>

<li><a href="Parenthesome" title="Parenthesome">Parenthesome</a></li>

<li><a href="Autophagosome" title="Autophagosome">Autophagosome</a></li>

<li><a href="Vesicle_(biology_and_chemistry)" title="Vesicle (biology and chemistry)">Vesicle</a>

<ul><li><a href="Exosome_(vesicle)" title="Exosome (vesicle)">Exosome</a></li>

<li><a href="Lysosome" title="Lysosome">Lysosome</a></li>

<li><a href="Endosome" title="Endosome">Endosome</a></li>

<li><a href="Phagosome" title="Phagosome">Phagosome</a></li>

<li><a href="Vacuole" title="Vacuole">Vacuole</a></li>

<li><a href="Acrosome" title="Acrosome">Acrosome</a></li></ul></li>

<li><a href="Granule_(cell_biology)" title="Granule (cell biology)">Cytoplasmic granule</a>

<ul><li><a href="Melanosome" title="Melanosome">Melanosome</a></li>

<li><a href="Microbody" title="Microbody">Microbody</a></li>

<li><a href="Glyoxysome" title="Glyoxysome">Glyoxysome</a></li>

<li><a href="Peroxisome" title="Peroxisome">Peroxisome</a></li>

<li><a href="Weibel%E2%80%93Palade_body" title="Weibel–Palade body">Weibel–Palade body</a></li></ul></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Cytoskeleton" title="Cytoskeleton">Cytoskeleton</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Microfilament" title="Microfilament">Microfilament</a></li>

<li><a href="Intermediate_filament" title="Intermediate filament">Intermediate filament</a></li>

<li><a href="Microtubule" title="Microtubule">Microtubule</a></li>

<li><a href="Prokaryotic_cytoskeleton" title="Prokaryotic cytoskeleton">Prokaryotic cytoskeleton</a></li>

<li><a href="Microtubule_organizing_center" title="Microtubule organizing center">Microtubule organizing center</a>

<ul><li><a href="Centrosome" title="Centrosome">Centrosome</a></li>

<li><a href="Centriole" title="Centriole">Centriole</a></li>

<li><a href="Basal_body" title="Basal body">Basal body</a></li>

<li><a href="Spindle_pole_body" title="Spindle pole body">Spindle pole body</a></li></ul></li>

<li><a href="Myofibril" title="Myofibril">Myofibril</a></li>

<li><a href="Undulipodium" title="Undulipodium">Undulipodium</a>

<ul><li><a href="Cilium" title="Cilium">Cilium</a></li>

<li><a href="Flagellum#Eukaryotic" title="Flagellum">Flagellum</a></li>

<li><a href="Axoneme" title="Axoneme">Axoneme</a></li>

<li><a href="Radial_spoke" title="Radial spoke">Radial spoke</a></li></ul></li>

<li><a href="Pseudopodium" class="mw-redirect" title="Pseudopodium">Pseudopodium</a>

<ul><li><a href="Lamellipodium" title="Lamellipodium">Lamellipodium</a></li>

<li><a href="Filopodium" class="mw-redirect" title="Filopodium">Filopodium</a></li></ul></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Endosymbiont" title="Endosymbiont">Endosymbionts</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Mitochondrion" title="Mitochondrion">Mitochondrion</a></li>

<li><a href="Plastid" title="Plastid">Plastid</a>

<ul><li><a href="Chloroplast" title="Chloroplast">Chloroplast</a></li>

<li><a href="Chromoplast" title="Chromoplast">Chromoplast</a></li>

<li><a href="Gerontoplast" title="Gerontoplast">Gerontoplast</a></li>

<li><a href="Leucoplast" title="Leucoplast">Leucoplast</a></li>

<li><a href="Amyloplast" title="Amyloplast">Amyloplast</a></li>

<li><a href="Elaioplast" title="Elaioplast">Elaioplast</a></li>

<li><a href="Proteinoplast" title="Proteinoplast">Proteinoplast</a></li>

<li><a href="Tannosome" title="Tannosome">Tannosome</a></li>

<li><a href="Apicoplast" title="Apicoplast">Apicoplast</a></li></ul></li>

<li><a href="Nitroplast" title="Nitroplast">Nitroplast</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other internal</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Nucleolus" title="Nucleolus">Nucleolus</a></li>

<ul><li><a href="Ribosome" title="Ribosome">Ribosome</a></li>

<li><a href="Spliceosome" title="Spliceosome">Spliceosome</a></li>

<li><a href="Vault_(organelle)" title="Vault (organelle)">Vault</a></li></ul></li>

<li><a href="Cytoplasm" title="Cytoplasm">Cytoplasm</a>

<ul><li><a href="Cytosol" title="Cytosol">Cytosol</a></li>

<li><a href="Cytoplasmic_inclusion" class="mw-redirect" title="Cytoplasmic inclusion">Inclusions</a></li></ul></li>

<li><a href="Proteasome" title="Proteasome">Proteasome</a></li>

<li><a href="Magnetosome" title="Magnetosome">Magnetosome</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">External</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Extracellular_matrix" title="Extracellular matrix">Extracellular matrix</a></li></ul>

</div></td></tr></tbody></table></div>

<div class="navbox-styles"></div><div role="navigation" class="navbox" aria-labelledby="Microbiology:_Bacteria461" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2" style="text-align: center;"><div id="Microbiology:_Bacteria461" style="font-size:114%;margin:0 4em"><a href="Microbiology" title="Microbiology">Microbiology</a>: <a href="Bacteria" title="Bacteria">Bacteria</a></div></th></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%"><a href="Medical_microbiology" title="Medical microbiology">Medical<br>microbiology</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Pathogenic_bacteria" title="Pathogenic bacteria">Infection</a></li>

<li><a href="Exotoxin" title="Exotoxin">Exotoxin</a></li>

<li><a href="Lysogenic_cycle" title="Lysogenic cycle">Lysogenic cycle</a></li>

<li><a href="Pathogenic_bacteria" title="Pathogenic bacteria">Pathogenic bacteria</a></li>

<li><a href="Antimicrobial_resistance" title="Antimicrobial resistance">Resistance</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%"><a href="Biochemistry" title="Biochemistry">Biochemistry</a><br>and <a href="Ecology" title="Ecology">ecology</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">Oxygen<br>preference</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Aerobic_organism" title="Aerobic organism">Aerobic</a>

<ul><li><a href="Obligate_aerobe" title="Obligate aerobe">Obligate</a></li>

<li><a href="Facultative_aerobe" class="mw-redirect" title="Facultative aerobe">Facultative</a></li></ul></li>

<li><a href="Anaerobic_organism" title="Anaerobic organism">Anaerobic</a>

<ul><li><a href="Facultative_anaerobic_organism" title="Facultative anaerobic organism">Facultative</a></li>

<li><a href="Obligate_anaerobe" title="Obligate anaerobe">Obligate</a></li></ul></li>

<li><a href="Microaerophile" title="Microaerophile">Microaerophile</a></li>

<li><a href="Nanaerobe" title="Nanaerobe">Nanaerobe</a></li>

<li><a href="Aerotolerant_anaerobe" title="Aerotolerant anaerobe">Aerotolerant</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">Other</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Extremophile" title="Extremophile">Extremophile</a></li>

<li><a href="Human_microbiome" title="Human microbiome">Human microbiome</a>

<li><a href="Oral_microbiology" title="Oral microbiology">Mouth</a></li>

<li><a href="Vaginal_flora" title="Vaginal flora">Vaginal</a> (<a href="Vaginal_microbiota_in_pregnancy" class="mw-redirect" title="Vaginal microbiota in pregnancy">in pregnancy</a>)</li>

<li><a href="Placental_microbiome" title="Placental microbiome">Placental</a></li>

<li><a href="Uterine_microbiome" title="Uterine microbiome">Uterine</a></li>

<li><a href="Salivary_microbiome" title="Salivary microbiome">Salivary</a></li></ul></li>

<li><a href="Microbial_metabolism" title="Microbial metabolism">Microbial metabolism</a></li>

<li><a href="Nitrogen_fixation" title="Nitrogen fixation">Nitrogen fixation</a></li>

<li><a href="Microbial_ecology" title="Microbial ecology">Microbial ecology</a></li>

<li><a href="Primary_nutritional_groups" title="Primary nutritional groups">Primary nutritional groups</a></li>

<li>Substrate preference

<ul><li><a href="Lipophilic_bacteria" title="Lipophilic bacteria">Lipophilic</a></li>

<li><a href="Osmophile" title="Osmophile">Saccharophilic</a></li></ul></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%">Shape</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Bacterial_cellular_morphologies" title="Bacterial cellular morphologies">Bacterial cellular morphologies</a>

<ul><li><a href="Bacterial_cell_structure" title="Bacterial cell structure">cell structure</a></li>

<li><a href="Bacterial_morphological_plasticity" title="Bacterial morphological plasticity">plasticity</a></li></ul></li>

<li><a href="Coccus" class="mw-redirect" title="Coccus">Cocci</a></li>

<li><a href="Bacillus_(shape)" class="mw-redirect" title="Bacillus (shape)">Bacilli</a></li>

<li><a href="Coccobacillus" class="mw-redirect" title="Coccobacillus">Coccobacilli</a></li>

<li><a href="Spiral_bacteria" class="mw-redirect" title="Spiral bacteria">Spiral</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%"><a href="Bacterial_cell_structure" title="Bacterial cell structure">Structure</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;"></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Cell_membrane" title="Cell membrane">Cell membrane</a></li>

<li><a href="Cell_wall" title="Cell wall">Cell wall</a>: <a href="Peptidoglycan" title="Peptidoglycan">Peptidoglycan</a>

<li><i><a href="Gram-positive_bacteria" title="Gram-positive bacteria">Gram-positive bacteria</a> only:</i> <a href="Teichoic_acid" title="Teichoic acid">Teichoic acid</a></li>

<li><a href="Lipoteichoic_acid" title="Lipoteichoic acid">Lipoteichoic acid</a></li>

<li><a href="Endospore" title="Endospore">Endospore</a></li>

<li><i><a href="Gram-negative_bacteria" title="Gram-negative bacteria">Gram-negative bacteria</a> only:</i> <a href="Bacterial_outer_membrane" title="Bacterial outer membrane">Bacterial outer membrane</a>

<ul><li><a href="General_bacterial_porin_family" title="General bacterial porin family">Porin</a></li>

<li><a href="Lipopolysaccharide" title="Lipopolysaccharide">Lipopolysaccharide</a></li></ul></li>

<li><a href="Periplasmic_space" class="mw-redirect" title="Periplasmic space">Periplasmic space</a></li>

<li><i><a href="Mycobacterium" title="Mycobacterium">Mycobacteria</a> only:</i> <a href="Arabinogalactan" title="Arabinogalactan">Arabinogalactan</a></li>

<li><a href="Mycolic_acid" title="Mycolic acid">Mycolic acid</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">Outside<br>envelope</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Bacterial_capsule" title="Bacterial capsule">Bacterial capsule</a></li>

<li><a href="Slime_layer" title="Slime layer">Slime layer</a></li>

<li><a href="S-layer" title="S-layer">S-layer</a></li>

<li><a href="Glycocalyx" title="Glycocalyx">Glycocalyx</a></li>

<li><a href="Pilus" title="Pilus">Pilus</a></li>

<li><a href="Fimbria_(bacteriology)" class="mw-redirect" title="Fimbria (bacteriology)">Fimbria</a></li>

<li><a href="Non-motile_bacteria" title="Non-motile bacteria">Non-motile bacteria</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">Composite</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Biofilm" title="Biofilm">Biofilm</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%"><a href="Bacterial_taxonomy" title="Bacterial taxonomy">Taxonomy</a><br>and <a href="Evolution_of_bacteria" title="Evolution of bacteria">evolution</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="https://species.wikimedia.org/wiki/Bacteria_(classifications)" class="extiw external" title="wikispecies:Bacteria (classifications)">Bacteria (classifications)</a></li>

<li><a href="Bacterial_phyla" title="Bacterial phyla">Bacterial phyla</a></li>

<li><i>Former groupings</i>: <a href="Schizomycetes" class="mw-redirect" title="Schizomycetes">Schizomycetes</a></li>

<li><a href="Monera" title="Monera">Monera</a></li>

<li><a href="Prokaryota" class="mw-redirect" title="Prokaryota">Prokaryota</a>

<ul><li><a href="Gracilicutes" title="Gracilicutes">Gracilicutes</a></li>

<li><a href="Bacillota" title="Bacillota">Firmicutes</a></li>

<li><a href="Mollicutes" title="Mollicutes">Mollicutes</a></li>

<li><a href="Mendosicutes" class="mw-redirect" title="Mendosicutes">Mendosicutes</a></li></ul></li></ul>

</div></td></tr><tr><td class="navbox-abovebelow hlist" colspan="2" style="text-align: center;"><div>

<ul><li><span class="noviewer" typeof="mw:File"><span title="Category"></span></span> Category</li>

<li><span class="noviewer" typeof="mw:File"><span title="Commons page"></span></span> <a href="https://commons.wikimedia.org/wiki/Category:Bacteria" class="extiw external" title="commons:Category:Bacteria">Commons</a></li></ul>

</div></td></tr></tbody></table></div></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2024-05-12" href="https://en.wikipedia.org/wiki/?title=Cell_envelope&oldid=1223435205">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

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