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Bacterial cell structure

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	Topics Bacterial cell structure Topic Home BacteriaBacteria Bacteria are a major group of living organisms.... , despite their apparent simplicity, contain a well developed cell structure which is responsible for many of their unique biological properties. Many structural features are unique to bacteriaBacteria Bacteria are a major group of living organisms.... and are not found among archaeaArchaea Archaea , also called Archaebacteria , is a major division of living organisms.... or eukaryotes. Because of the simplicity of bacteriaBacteria Bacteria are a major group of living organisms.... relative to larger organisms and the ease with which they can be manipulated experimentally, the cell structure of bacteriaBacteria Bacteria are a major group of living organisms.... has been well studied, revealing many biochemical principles that have been subsequently applied to other organisms. Cell morphology Perhaps the most elemental structural property of bacteriaFacts About Bacteria Bacteria are a major group of living organisms.... is cell morphologyMorphology (biology) The term morphology in biology refers to the outward appearance of an organism or taxon and its component parts.... (shape). Typical examples include: coccusCoccus ... (spherical) bacillus (rod-like) spirillumSpirillum Spirillum in microbiology refers to a bacterium with a cell body that twists like a spiral.... (spiral) filamentousFilamentation Filamentation is the anomal growth of certain bacteria, such as E.... Cell shape is generally characteristic of a given bacterial species, but can vary depending on growth conditions. Some bacteria have complex life cycles involving the production of stalks and appendages (e.g. Caulobacter) and some produce elaborate structures bearing reproductive spores (e.g. Myxococcus, StreptomycesStreptomyces Summary *Streptomyces* is a genus of Actinobacteria, a group of Gram-positive and generally high GC-content bacteria.... ). BacteriaBacteria Bacteria are a major group of living organisms.... generally form distinctive cell morphologies when examined by light microscopyMicroscopy Microscopy is any technique for producing visible images of structures or details too small to otherwise be seen by the huma... and distinct colony morphologies when grown on Petri plates. These are often the first characteristics observed by a microbiologistMicrobiologist A microbiologist is a biologist that studies the field of microbiology.... to determine the identity of an unknown bacterial culture. The importance of cell size Perhaps the most obvious structural characteristic of bacteriaBacteria Bacteria are a major group of living organisms.... is (with some exceptions) their small size. For example, Escherichia coliEscherichia coli *Escherichia coli* , usually abbreviated to E.... , an "average" sized bacterium with average cell length of ca. 1 µm has a cell volume of approximately 1 - 2 µm³. This corresponds to a wet mass of ca. 1 pg, assuming that the cell consists mostly of water. The dry mass of a single cell can be estimated as 20 % of the wet mass, amounting to 0.2 pg. About half of the dry mass of a bacterial cell consists of carbon, and also about half of it can be attributed to proteins. Therefore, a typical fully grown 1-liter culture of Escherichia coliEscherichia coli *Escherichia coli* , usually abbreviated to E.... (at an optical density of 1.0, corresponding to ca. 10⁹ cells/ml) yields ca. 1 g wet cell mass. Small size is extremely important because it allows for a large surface area-to-volume ratio which allows for rapid uptake and intracellular distribution of nutrients and excretion of wastes. At low surface area-to-volume ratios the diffusion of nutrients and waste products across the bacterial cell membrane limits the rate at which microbial metabolism can occur, making the cell less evolutionarily fit. The reason for the existence of large cells is unknown, although it is speculated that the increased cell volume is used primarily for storage of excess nutrients. The bacterial cell wall As in other organisms, the bacterial cell wallCell wall A cell wall is a more or less solid layer surrounding a cell.... provides structural integrity to the cell. In prokaryotes, the primary function of the cell wall is to protect the cell from internal turgor pressureTurgor pressure Summary Turgor pressure or turgidity is the positive internal pressure in a cell resulting from osmotic pressure.... 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 peptidoglycanPeptidoglycan Summary Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a homogeneous layer ... (poly-N-acetylglucosamine and N-acetylmuramic acid), which is located immediately outside of the cytoplasmic membrane. PeptidoglycanPeptidoglycan Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a homogeneous layer ... 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 permiability barrier for small substrates. While all bacterial cell walls (with a few exceptions e.g. intracellular parasites such as MycoplasmaFacts About Mycoplasma *Mycoplasma* is a genus of small microorganisms that resemble bacteria which lack cell walls, but have many differences an... ) contain peptidoglycan, not all cell walls have the same overall structures. There are two main types of bacterial cell walls, Gram positive and Gram negative, which are differentiated by their Gram stainingGram staining Gram staining is an empirical method of differentiating bacterial species into two large groups based on the chemical and ... characteristics. For both Gram-positive and Gram-negative bacteria, particles of approximately 2 nm can pass through the peptidoglycan. The Gram positive cell wall The Gram positive cell wall is characterized by the presence of a very thick peptidoglycanPeptidoglycan Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a homogeneous layer ... layer, which is responsible for the retention of the crystal violet dyes during the Gram stainingGram staining Gram staining is an empirical method of differentiating bacterial species into two large groups based on the chemical and ... procedure. It is found exclusively in organisms belonging to the ActinobacteriaActinobacteria The Actinobacteria or Actinomycetes are a group of Gram-positive bacteria.... (or high %G+C Gram positive organisms) and the FirmicutesFirmicutes The Firmicutes are a division of bacteria, most of which have Gram-positive stains.... (or low %G+C Gram positive organisms). Bacteria within the Deinococcus-ThermusDeinococcus-Thermus The Deinococcus-Thermus are a small group of bacteria comprised of cocci highly resistant to environmental hazards.... group may also exhibit Gram positive staining behaviour but contain some cell wall structures typical of Gram negative organisms. Imbedded in the Gram positive cell wall are polyalcohols called teichoic acidTeichoic acid Teichoic acids are polymers of glycerol or ribitol linked via phosphodiester bonds.... s, some of which are lipid-linked to form lipoteichoic acidsTeichoic acid Teichoic acids are polymers of glycerol or ribitol linked via phosphodiester bonds.... . Because lipoteichoic acidsTeichoic acid Teichoic acids are polymers of glycerol or ribitol linked via phosphodiester bonds.... are covalently linked to lipids within the cytoplasmic membrane they are responsible for linking the peptidoglycanPeptidoglycan Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a homogeneous layer ... to the cytoplasmic membrane. Teichoic acidTeichoic acid Teichoic acids are polymers of glycerol or ribitol linked via phosphodiester bonds.... s give the Gram positive cell wall an overall negative charge due to the presence of phosphodiester bonds between teichoic acidTeichoic acid Teichoic acids are polymers of glycerol or ribitol linked via phosphodiester bonds.... monomers. The Gram negative cell wall Unlike the Gram positive cell wall, the Gram negative cell wall contains a thin peptidoglycanPeptidoglycan Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a homogeneous layer ... layer adjacent to the cytoplasmic membrane, which is responsible for the cell wall's inability to retain the crystal violet stain upon decolourisation with ethanol during Gram stainingGram staining Gram staining is an empirical method of differentiating bacterial species into two large groups based on the chemical and ... . In addition to the peptidoglycanPeptidoglycan Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a homogeneous layer ... layer, the Gram negative cell wall also contains an additional outer membrane composed by phospholipidPhospholipid Phospholipids are a class of lipids formed from four components: fatty acids, a negatively-charged phosphate group, nitrogen... s and lipopolysaccharideLipopolysaccharide A lipopolysaccharide is any of a class of large molecules consisting of a lipid and a polysaccharide joined by a covalent bo... s which face into the external environment. As the lipopolysaccharideLipopolysaccharide A lipopolysaccharide is any of a class of large molecules consisting of a lipid and a polysaccharide joined by a covalent bo... s are highly-charged, the Gram negative cell wall has an overall negative charge. The chemical structure of the outer membrane lipopolysaccharideLipopolysaccharide A lipopolysaccharide is any of a class of large molecules consisting of a lipid and a polysaccharide joined by a covalent bo... s is often unique to specific bacterial strains (i.e. sub-species) and is responsible for many of the antigenAntigen An antigen is a substance that stimulates an immune response, especially the production of antibodies.... ic properties of these strains. The bacterial cytoplasmic membrane The bacterial cytoplasmic membrane is composed of a phospholipid bilayer and thus has all of the general functions of a cell membraneCell membrane A cell membrane, plasma membrane or plasmalemma is a selectively permeable lipid bilayer coated by proteins whi... such as acting as a permeability barrier for most molecules and serving as the location for the transport of molecules into the cell. In addition to these functions, prokaryotic membranes also function in energy conservation as the location about which a proton motive force is generated. Unlike eukaryotes, bacterial membranes (with some exceptions e.g. MycoplasmaMycoplasma *Mycoplasma* is a genus of small microorganisms that resemble bacteria which lack cell walls, but have many differences an... and methanotrophs) generally do not contain sterols. However, many microbes do contain structurally related compounds called hopanoids which likely fulfill the same function. Unlike eukaryotes, bacteriaBacteria Overview Bacteria are a major group of living organisms.... can have a wide variety of fatty acidFatty acid In chemistry, especially biochemistry, a fatty acid is a carboxylic acid , often with a long aliphatic tail , either saturat... s within their membranes. Along with typical saturated and unsaturated fatty acidFacts About Fatty acid In chemistry, especially biochemistry, a fatty acid is a carboxylic acid , often with a long aliphatic tail , either saturat... s, bacteria can contain fatty acids with additional methyl, hydroxyHydroxy In chemical nomenclature, the prefix *hydroxy* indicates the presence of a hydroxyl functional group '.... or even cyclic groups. The relative proportions of these fatty acids can be modulated by the bacterium to maintain the optimum fluidity of the membrane (e.g. following temperature change). As a phospholipid bilayer, the lipid portion of the outer membrane is impermeable to charged molecules. However, channels called porinPorin (protein) Porins are transmembrane proteins that are large enough to facilitate passive diffusion.... s are present in the outer membrane that allow for passive transportPassive transport Passive transport is a means of moving biochemicals, and other atomic or molecular substances, across membranes.... of many ionIon An ion is an atom or group of atoms that normally are electrically neutral and achieve their status as an ion by loss of an... s, sugarSugar In general use, non-scientists take "sugar" to mean sucrose, also called "table sugar" or saccharose, a white crystalline solid di... s and amino acidAmino acid In chemistry, an amino acid is any molecule that contains both amine and carboxyl functional groups.... s across the outer membrane. These molecules are therefore present in the periplasm, the region between the cytoplasmic and outer membranes. The periplasm contains the peptidoglycan layer and many proteins responsible for substrate binding or hydrolysisHydrolysis Hydrolysis is a chemical reaction or process in which a molecule is split into two parts by reacting with a molecule of wate... and reception of extracellular signals. The periplasm it is thought to exist as a gel-like state rather than a liquid due to the high concentration of proteins and peptidoglycanPeptidoglycan Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a homogeneous layer ... 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 cytoplasmic membrane using transport and signalling proteins imbedded there. Other bacterial surface structures Fimbrae and Pili Main article: PilusFacts About Pilus A pilus is a hairlike structure on the surface of a cell, especially Gram-negative bacteria, a protein appendage required f... Fimbrae are protein tubes that extend out from the outer membrane in many members of the ProteobacteriaProteobacteria The Proteobacteria are a major group of bacteria.... . They are generally short in length and present in high numbers about the entire bacterial cell surface. Fimbrae usually function to facilitate the attachment of a bacterium to a surface (e.g. to form a biofilmBiofilm A biofilm is a complex aggregation of microorganisms marked by the excretion of a protective and adhesive matrix.... ) or to other cells (e.g. animal cells during pathogenesisPathogenesis Pathogenesis is the mechanism by which a certain etiological factor causes disease.... )). A few organisms (e.g. Myxococcus) use fimbrae for motility to facilitate the assembly of multicellular structures such as fruiting bodiesFruiting body Summary In fungi, the fruiting body is a multicellular structure on which spore-producing structures, such as basidia or asci, are b... . PiliPilus A pilus is a hairlike structure on the surface of a cell, especially Gram-negative bacteria, a protein appendage required f... are similar in structure to fimbrae but are much longer and present on the bacterial cell in low numbers. PiliFacts About Pilus A pilus is a hairlike structure on the surface of a cell, especially Gram-negative bacteria, a protein appendage required f... are involved in the process of bacterial conjugationBacterial conjugation Bacterial conjugation is the transfer of genetic material between bacteria through cell-to-cell contact.... . Non-sex pili also aid bacteria in gripping surfaces. S-layers Main article: S-layerS-layer An S-layer is a cell membrane commonly found in gram-positive and gram-negative bacteria, as well as among Archaea.... An S-layerS-layer An S-layer is a cell membrane commonly found in gram-positive and gram-negative bacteria, as well as among Archaea.... is a cell surface protein layer found in many different bacteriaBacteria Bacteria are a major group of living organisms.... and in some archaeaArchaea Archaea , also called Archaebacteria , is a major division of living organisms.... where it serves as the cell wall. All S-layerS-layer An S-layer is a cell membrane commonly found in gram-positive and gram-negative bacteria, as well as among Archaea.... s are made up of a two-dimensional array of proteins and have a crystalline appearance, the symmetry of which differs between species. The exact function of S-layerS-layer An S-layer is a cell membrane commonly found in gram-positive and gram-negative bacteria, as well as among Archaea.... s is unknown, but it has been suggested that they act as a partial permeability barrier for large substrates. For example, an S-layerS-layer An S-layer is a cell membrane commonly found in gram-positive and gram-negative bacteria, as well as among Archaea.... could conceivably keep extracellular proteins near the cell membrane by preventing their diffusion away from the cell. In some pathogenic species, an S-layerS-layer An S-layer is a cell membrane commonly found in gram-positive and gram-negative bacteria, as well as among Archaea.... may help to facilitate survival within the host by conferring protection against host defence mechanisms. Capsules and Slime Layers Main article: Slime layerSlime layer A slime layer in bacteria is an easily removed, diffuse, unorganised layer of extracellular material that surrounds bacteria... Many bacteriaBacteria Bacteria are a major group of living organisms.... secrete extracellular polymers outside of their cell walls. These polymers are usually composed of polysaccharidePolysaccharide Polysaccharides are relatively complex carbohydrates.... s and sometimes proteinProtein Proteins are large organic compounds made of amino acids arranged in a linear chain and joined by peptide bonds.... . Capsules are relatively impermeable structures that cannot be stained with dyes such as India inkIndia ink Overview India ink , also called Chinese ink since it may have been first developed in either China or India, is a simple black... . They are structures that help protect bacteriaBacteria Bacteria are a major group of living organisms.... from phagocytosisPhagocytosis Phagocytosis is a form of endocytosis wherein large particles are enveloped by the cell membrane of a cell and internalized ... and desiccationFacts About Desiccation Desiccation is the state of extreme dryness, or the process of extreme drying.... . Slime layerSlime layer A slime layer in bacteria is an easily removed, diffuse, unorganised layer of extracellular material that surrounds bacteria... s are somewhat looser, fibrous structures generally involved in attachment of bacteriaBacteria Bacteria are a major group of living organisms.... to other cells or inanimate surfaces to form biofilmBiofilm A biofilm is a complex aggregation of microorganisms marked by the excretion of a protective and adhesive matrix.... s. Slime layers can also be used as a food reserve for the cell. An example of how a bacterial cell uses their slime layer to attach to a surface is in the Streptococcus mutans. Streptococcus mutans attaches to the teeth with a slime layer and forms a sticky film that traps food particles and other bacteria on the teeth (dental plaque). The bacteria then metabolizes the trapped food particles and release acids (thus possibly causing tooth decay). Flagella Main article: FlagellumFlagellum A flagellum ' is a whip-like organelle that many unicellular organisms, and some multicellular ones, use to move about.... Perhaps the most recognizable extracellular bacterial cell structures are flagella. Flagella are whip-like structures protruding from the bacterial cell wall and are responsible for bacterial motilityMotility Motility is a biological term which refers to the ability to move spontaneously and independently.... (i.e. movement). The arrangement of flagella about the bacterial cell is unique to the species observed. Common forms include: Peritrichous - Multiple flagella found at several locations about the cell PolarPolar Polar may refer to:As a noun:... - Single flagella found at one or both cell poles Lophotrichous - A tuft of flagella found at one cell pole Flagella are complex structures that are composed of many different proteins. These include flagellinFlagellin Flagellin is a protein that arranges itself in a hollow cylinder to form the filament in bacterial flagellum.... , which makes up the whip-like tube and a proteinProtein Proteins are large organic compounds made of amino acids arranged in a linear chain and joined by peptide bonds.... complex that spans the cell wall and cell membrane to form a motor that causes the flagellumFlagellum Overview A flagellum ' is a whip-like organelle that many unicellular organisms, and some multicellular ones, use to move about.... to rotate. This rotation is normally driven by proton motive force and are found in the body of the cell. Intracellular bacterial cell structures In comparison to eukaryotes, the intracellular features of the bacterial cell are extremely simplistic. Bacteria do not contain organelleOrganelle In cell biology, an organelle is a discrete structure of a cell having specialized functions.... s in the same sense as eukaryoteEukaryote \|-\| style = "background: pink; padding: 4px;" \| Animalia - Animals... s. Instead, the chromosomeChromosome Overview A chromosome is a large macromolecule into which DNA is normally packaged in a cell.... and perhaps ribosomes are the only easily observable intracellular structures found in all bacteriaBacteria Bacteria are a major group of living organisms.... . There do exist, however, specialized groups of bacteria that contain more complex intracellular structures, some of which are discussed below. The bacterial chromosome and plasmids Main article: PlasmidFacts About Plasmid A plasmid is a DNA molecule separate from the chromosomal DNA and capable of autonomous replication.... Unlike eukaryotes, the bacterial chromosomeChromosome A chromosome is a large macromolecule into which DNA is normally packaged in a cell.... is not enclosed inside of a membrane-bound nucleusCell nucleus Overview In cell biology, the nucleus is an organelle found in most eukaryotic cells.... but instead resides inside the bacterial cytoplasmCytoplasm Cytoplasm is a jelly-like material that fills cells.... . This means that the transfer of cellular information through the processes of translationTranslation Translation is an activity comprising the interpretation of the meaning of a text in one language — the source text'... , transcriptionFacts About Transcription (genetics) Transcription is the process through which a DNA sequence is enzymatically copied by an RNA polymerase to produce a complem... and DNA replicationDNA replication DNA replication or DNA synthesis is the process of copying a double-stranded DNA strand in a cell, prior to cell divis... all occur within the same compartment and can interact with other cytoplasmic structures, most notably ribosomeRibosome A ribosome is an organelle composed of ribosomal RNA and ribosomal proteins .... s. The bacterial chromosome is not packaged using histones to form chromatinChromatin Chromatin is a complex of DNA and protein found inside the nuclei of eukaryotic cells.... as in eukaryoteEukaryote \|-\| style = "background: pink; padding: 4px;" \| Animalia - Animals... s but instead exists as a highly compact supercoiled structure, the precise nature of which remains unclear. Most bacterial chromosomes are circular although some examples of linear chromosomes exist (e.g. Borrelia burgdorferiBorrelia burgdorferi *Borrelia burgdorferi* is a spirochete bacteria and the causative agent of Lyme disease, its most commonly transmitted to ... ). Along with chromosomal DNA, most bacteria also contain small independent pieces of DNA called plasmidPlasmid A plasmid is a DNA molecule separate from the chromosomal DNA and capable of autonomous replication.... s that often encode for traits that are advantageous but not essential to their bacterial host. PlasmidPlasmid Summary A plasmid is a DNA molecule separate from the chromosomal DNA and capable of autonomous replication.... s can be easily gained or lost by a bacterium and can be transferred between bacteria as a form of horizontal gene transferHorizontal gene transfer Horizontal gene transfer, also Lateral gene transfer, is any process in which an organism transfers genetic material t... . Ribosomes and other multiprotein complexes Main article: RibosomeRibosome A ribosome is an organelle composed of ribosomal RNA and ribosomal proteins .... In most bacteriaBacteria Bacteria are a major group of living organisms.... the most numerous intracellular structure is the ribosomeRibosome A ribosome is an organelle composed of ribosomal RNA and ribosomal proteins .... , the site of protein synthesisProtein biosynthesis Overview Protein biosynthesis is the process in which cells build proteins.... in all living organisms. All prokaryotes have 70S (where S=SvedbergFacts About Svedberg A Svedberg is a non-SI physical unit used in ultracentrifugation.... units) ribosomes while eukaryotes contain larger 80S ribosomeRibosome A ribosome is an organelle composed of ribosomal RNA and ribosomal proteins .... s in their cytosolCytosol The cytosol is the internal fluid of the cell, and a portion of cell metabolism occurs here.... . The 70S ribosomeRibosome Summary A ribosome is an organelle composed of ribosomal RNA and ribosomal proteins .... is made up of a 50S and 30S subunits. The 50S subunit contains the 23S and 5S rRNA while the 30S subunit contains the 16S rRNA. These rRNA molecules differ in size in eukaryotes and are complexed with a large number of ribosomal proteins, the number and type of which can vary slightly between organisms. While the ribosomeRibosome A ribosome is an organelle composed of ribosomal RNA and ribosomal proteins .... is the most commonly observed intracellular multiprotein complex in bacteriaBacteria Bacteria are a major group of living organisms.... other large complexes do occur and can sometimes be seen using microscopyMicroscopy Microscopy is any technique for producing visible images of structures or details too small to otherwise be seen by the huma... . Intracellular membranes While not typical of all bacteriaBacteria Bacteria are a major group of living organisms.... some microbes contain intracellular membranes in addition to (or as extensions of) their cytoplasmic membranes. An early idea was that bacteria might contain membrane folds termed mesosomeMesosome Mesosomes are the invaginations of the plasma membrane that can form into vesicles.... s, but these were later shown to be artifacts produced by the chemicals used to prepare the cells for electron microscopy. Examples of bacteriaBacteria Bacteria are a major group of living organisms.... containing intracellular membranes are phototrophPhototroph Phototrophs or photoautotrophs are photosynthetic algae, fungi, bacteria and cyanobacteria which build up carbon dioxide and... s, nitrifying bacteriaNitrifying bacteria Summary Nitrifying bacteria are bacteria that are able to grow chemolithotrophically at the expense of inorganic nitrogen compounds.... and methaneMethane The simplest hydrocarbon, methane, is a gas with a chemical formula of CH4.... -oxidising bacteria. Intracellular membranes are also found in bacteriaBacteria Bacteria are a major group of living organisms.... belonging to the poorly studied PlanctomycetesPlanctomycetes Planctomycetes are an order of obligately aerobic aquatic bacteria and are found in field samples of brackish, and marine ... group, although these membranes more closely resemble organellar membranes in eukaryotes and are currently of unknown function. Cytoskeleton The prokaryotic cytoskeleton is the collective name for all structural filamentsProtein filament Overview In biology, a filament is a long chain of proteins, such as those found in hair, muscle, or in flagella.... in prokaryotes. It was once thought that prokaryotic cells did not possess cytoskeletonsCytoskeleton ... , but recent advances in visualization technology and structure determination have shown that filaments indeed exist in these cells. In fact, homologues for all major cytoskeletal proteins in eukaryotes have been found in prokaryotes. Cytoskeletal elements play essential roles in cell divisionCell division Cell division is the process by which a cell, called the parent cell, divides into two cells, called daughter cells.... , protection, shape determination, and polarity determination in various prokaryotes. Nutrient storage structures Most bacteriaBacteria Bacteria are a major group of living organisms.... l habitats do not live in environments that contain large amounts of essential nutrients at all times. To accommodate these transient levels of nutrients bacteriaBacteria Overview Bacteria are a major group of living organisms.... contain several different methods of nutrient storage in times of plenty for use in times of want. For example, many bacteriaBacteria Bacteria are a major group of living organisms.... store excess carbon in the form of polyhydroxyalkanoatesPolyhydroxybutyrate Polyhydroxybutyrate is a polyhydroxyalkanoate, a polymer belonging to the polyesters class that was first isolated and chara... or glycogenGlycogen Glycogen is a polysaccharide that is the principal storage form of glucose in animal and human cells.... . Some microbes store soluble nutrients such as nitrateNitrate In inorganic chemistry, a nitrate is a salt of nitric acid.... in vacuoleVacuole Vacuoles are membrane-bounded compartments within some eukaryotic cells that can serve a variety of secretory, excretory, an... s. Sulfur is most often stored as elemental (S⁰) granules which can be deposited either intra- or extracellularly. Sulfur granules are especially common in bacteriaBacteria Bacteria are a major group of living organisms.... that use hydrogen sulfideHydrogen sulfide Hydrogen sulfide, H2S, is a colorless, toxic, flammable gas that is responsible for the foul odor of rotten eggs and flatule... as an electron source. Most of the above mentioned examples can be viewed using a microscopeMicroscope A microscope is an instrument for viewing objects that are too small to be seen by the naked or unaided eye.... and are surrounded a thin nonunit membrane to separate them from the cytoplasmCytoplasm Cytoplasm is a jelly-like material that fills cells.... . Gas vesicles Gas vesicles are spindle-shaped structures found in some planktonPlankton Plankton are drifting organisms that inhabit the water column of oceans, seas, and bodies of fresh water. ... ic bacteria that provides buoyancyBuoyancy Summary In physics, buoyancy is an upward force on an object immersed in a fluid, enabling it to float or at least to appear lighter... to these cells by decreasing their overall cell density. They are made up of a protein coat that is very impermeable to solvents such as water but permeable to most gases. By adjusting the amount of gas present in their gas vesicles bacteriaBacteria Bacteria are a major group of living organisms.... can increase or decrease their overall cell density and thereby move up or down within the water column to maintain their position in an environment optimal for growth. Carboxysomes Main article: CarboxysomeCarboxysome The carboxysome is a bacterial microcompartment made up of a protein shell that sequesters enzymes involved in carbon fixati... CarboxysomeCarboxysome The carboxysome is a bacterial microcompartment made up of a protein shell that sequesters enzymes involved in carbon fixati... s are intracellular structures found in many autotrophic bacteriaBacteria Bacteria are a major group of living organisms.... such as Cyanobacteria, Knallgasbacteria, Nitroso- and Nitrobacteria. They are proteinaceous structures resembling phage heads in their morphologyMorphology (biology) The term morphology in biology refers to the outward appearance of an organism or taxon and its component parts.... and contain the enzymes of carbon dioxide fixation in these organisms (especially ribulose bisphosphate carboxylase/oxygenase, RuBisCO, and carbonic anhydrase). It is thought that the high local concentration of the enzymes along with the fast conversion of bicarbonate to carbon dioxide by carbonic anhydrase allows faster and more efficient carbon dioxide fixation than possible inside the cytoplasm. Similar structures are known to harbor the coenzyme B12-containing glycerol dehydratase, the key enzyme of glycerol fermentation to 1,3-propanediol, in some Enterobacteriaceae (e. g. Salmonella). Magnetosomes Main article: MagnetosomeMagnetosome The magnetosome chains are membranous prokaryotic organelles present in magnetotactic bacteria.... MagnetosomeMagnetosome The magnetosome chains are membranous prokaryotic organelles present in magnetotactic bacteria.... s are intracellular structures found in magnetotactic bacteriaMagnetotactic bacteria Magnetotactic bacteria are a class of bacteria discovered in the 1960s, that exhibit the peculiar ability to orient themselv... that allow them to sense and align themselves along a magnetic field (magnetotaxis). The ecological role of magnetotaxis is unknown but it is hypothesized to be involved in the determination of optimal oxygen concentrations. MagnetosomeMagnetosome The magnetosome chains are membranous prokaryotic organelles present in magnetotactic bacteria.... s are composed of the mineral magnetiteMagnetite Magnetite is a ferrimagnetic mineral with IUPAC name iron oxide and with chemical formula Fe3O4, one of several ... and are surrounded by a nonunit membrane. The morphology of magnetosomeMagnetosome The magnetosome chains are membranous prokaryotic organelles present in magnetotactic bacteria.... s is species-specific. Endospores Main article: Endospores Perhaps the most well known bacterial adaptation to stress is the formation of endosporeEndospore An endospore is a dormant, tough, non-reproductive structure produced by a small number of bacteria from the Firmicute famil... s. EndosporeEndospore An endospore is a dormant, tough, non-reproductive structure produced by a small number of bacteria from the Firmicute famil... s are bacterial survival structures that are highly resistant to many different types of chemical and environmental stresses and therefore enable the survival of bacteriaBacteria Bacteria are a major group of living organisms.... in environments that would be lethal for these cells in their normal vegetative form. It has been proposed that endosporeEndospore An endospore is a dormant, tough, non-reproductive structure produced by a small number of bacteria from the Firmicute famil... formation has allowed for the survival of some bacteriaBacteria Bacteria are a major group of living organisms.... for hundreds of millions of years (e.g. in salt crystals) although these publications have been questioned. EndosporeFacts About Endospore An endospore is a dormant, tough, non-reproductive structure produced by a small number of bacteria from the Firmicute famil... formation is limited to several genera of Gram-positive bacteriaBacteria Bacteria are a major group of living organisms.... such as BacillusBacillus *Bacillus* is a genus of rod-shaped, Gram-positive bacteria and a member of the division Firmicutes.... and ClostridiumFacts About Clostridium *Clostridium* is a large genus of Gram-positive bacteria, belonging to the Firmicutes.... . It differs from reproductive spores in that only one spore is formed per cell resulting in no net gain in cell number upon endosporeEndospore An endospore is a dormant, tough, non-reproductive structure produced by a small number of bacteria from the Firmicute famil... germination. The location of an endosporeEndospore An endospore is a dormant, tough, non-reproductive structure produced by a small number of bacteria from the Firmicute famil... within a cell is species-specific and can be used to determine the identity of a bacterium. Further reading Madigan, M. T., Martinko, J. M. "Brock Biology of Microorganisms, 11th Ed." (2005) Pearson Prentice Hall, Upper Saddle River, NJ. External links