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Encyclopedia > Cell wall
Plant cells separated by transparent cell walls.
Plant cells separated by transparent cell walls.

A cell wall is a fairly rigid layer surrounding a cell, located external to the cell membrane, which provides the cell with structural support, protection, and acts as a filtering mechanism. The cell wall also prevents over-expansion when water enters the cell. They are found in plants, bacteria, archaea, fungi, and algae. Animals and most protists do not have cell walls. Image File history File linksMetadata No higher resolution available. ... Image File history File linksMetadata No higher resolution available. ... Plant cell structure Plant cells are eukaryotic cells that differ in several key respects from the cells of other eukaryotic organisms. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... The cell membrane (also called the plasma membrane, plasmalemma or phospholipid bilayer) is a selectively permeable lipid bilayer found in all cells. ... For other uses, see Plant (disambiguation). ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (pronounced ) are a group of prokaryotic and single-celled microorganisms. ... For the fictional character, see Fungus the Bogeyman. ... A seaweed (Laurencia) up close: the branches are multicellular and only about 1 mm thick. ... For other uses, see Animal (disambiguation). ... Typical phyla Chromalveolata Chromista Heterokontophyta Haptophyta Cryptophyta (cryptomonads) Alveolata Dinoflagellata Apicomplexa Ciliophora (ciliates) Cabozoa Excavata Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Archaeplastida (in part) Rhodophyta (red algae) Glaucophyta (basal archaeplastids) Amoebozoa Choanozoa Many others; classification varies Protists (IPA: (RP); (GenAm)), Greek protiston -a meaning the (most) first of all...


The cell wall is constructed from different materials dependent upon the species. In plants, the strongest component of the complex cell wall is a carbohydrate polymer called cellulose. In bacteria, peptidoglycan forms the cell wall. Archaea have various chemical compositions, including glycoprotein S-layers, pseudopeptidoglycan, or polysaccharides. Fungi possess cell walls of chitin, and algae typically possess walls constructed of glycoproteins and polysaccharides, however certain algal species may have a cell wall composed of silicic acid. Often, other accessory molecules are found anchored to the cell wall. Lactose is a disaccharide found in milk. ... A polymer (from Greek: πολυ, polu, many; and μέρος, meros, part) is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ... Cellulose as polymer of β-D-glucose Cellulose in 3D Cellulose (C6H10O5)n is a polysaccharide of beta-glucose. ... Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of eubacteria. ... N-linked protein glycosylation (N-glycosylation of N-glycans) at Asn residues (Asn-x-Ser/Thr motifs) in glycoproteins[1]. Glycoproteins are proteins that contain oligosaccharide chains (glycans) covalently attached to their polypeptide backbones. ... An S-layer is a part of cell envelope commonly found in gram-positive and gram-negative bacteria, as well as among Archaea. ... Pseudomurein (also known as pseudopeptidoglycan) is a major cell wall component of some archaebacteria that chemically differs from but morphologically, functionally, and structurally resembles eubacterial peptidoglycan. ... Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ... Structure of the chitin molecule, showing two of the N-Acetylglucosamine units that repeat to form long chains in beta-1,4 linkage. ... Silicic acid is a general name for a family of chemical compounds of silicon, hydrogen, and oxygen, with the general formula [SiOx(OH)4-2x]n. ...

Contents

Properties

Diagram of the plant cell, with the cell wall in green.

The cell wall serves a similar purpose in those organisms that possess them. The wall gives cells rigidity and strength, offering protection against mechanical stress. In multicellular organisms, it permits the organism to build and hold its shape (morphogenesis). The cell wall also limits the entry of large molecules that may be toxic to the cell. It further permits the creation of a stable osmotic environment by preventing osmotic lysis and helping to retain water. The composition, properties, and form of the cell wall may change during the cell cycle and depend on growth conditions. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Morphogenesis (from the Greek morphê shape and genesis creation) is one of three fundamental aspects of developmental biology along with the control of cell growth and cellular differentiation. ... The cell cycle, or cell-division cycle, is the series of events that take place in a eukaryotic cell leading to its replication. ...


Rigidity

In most cells, the cell wall is semi-rigid, meaning that it will bend somewhat rather than holding a fixed shape. This flexibility is seen when plants wilt, so that the stems and leaves begin to droop, or in seaweeds that bend in water currents. Wall rigidity seen in healthy plants results from a combination of the wall construction and turgor pressure. As John Howland states it: Ascophyllum nodosum exposed to the sun in Nova Scotia, Canada Dead Mans Fingers (Codium fragile) off Massachusetts coast For the band, see; Seaweed (band) For the rock musician, see; Seaweed (musician) Seaweeds are any of a large number of marine benthic algae. ... A current is the rate of fluid flow, especially water or air. ... This article or section does not cite its references or sources. ...

Think of the cell wall as a wicker basket in which a balloon has been inflated so that it exerts pressure from the inside. Such a basket is very rigid and resistant to mechanical damage. Thus does the prokaryote cell (and eukaryotic cell that possesses a cell wall) gain strength from a flexible plasma membrane pressing against a rigid cell wall.[1]

The rigidity of the cell wall thus results in part from inflation of the cell contained. This inflation is a result of the passive uptake of water. Osmosis is the spontaneous net movement of water across a semipermeable membrane from a region of low solute concentration to a solution with a high solute concentration, down a solute concentration gradient. ...


Other cell walls are inflexible. In plants, a secondary cell wall is a thicker additional layer of cellulose. Additional layers may be formed containing lignin in xylem cell walls, or containing suberin in cork cell walls. These compounds are rigid and waterproof, making the secondary wall stiff. Both wood and bark cells of trees have secondary walls. Other parts of plants such as the leaf stalk may acquire similar reinforcement to resist the strain of physical forces. Lignin (sometimes lignen) is a chemical compound (complex, highly cross-linked aromatic polymer) that is most commonly derived from wood and is an integral part of the cell walls of plants, especially in tracheids, xylem fibres and sclereids. ... In vascular plants, xylem is one of the two types of transport tissue, phloem being the other one. ... Suberin is a waxy substance found in higher plants. ... Cork cambium is a tissue found in many vascular plants as part of the periderm. ... mathematics, suppose ).C is a collection of mathematical objects (for instance sets or functions Then we say that C is rigid if every c ∈ C is uniquely determined by less information about c than one would expect. ... Waterproof fabrics are usually natural or synthetic fabrics that are laminated to or coated in some sort of permanently waterproofing material, such as rubber, polyvinyl chloride (PVC), polyurethane (PU), silicone elastomer, and wax. ... For other uses, see Wood (disambiguation). ... For other uses, see Bark (disambiguation). ... The coniferous Coast Redwood, the tallest tree species on earth. ... Leaf of Dog Rose (Rosa canina), showing the petiole and two leafy stipules In botany, the petiole is the small stalk attaching the leaf blade to the stem. ...


Certain single-cell protists and algae also produce a rigid wall. Diatoms build a frustule from silica extracted from the surrounding water; radiolarians also produce a test from minerals. Many green algae, such as the Dasycladales encase their cells in a secreted skeleton of calcium carbonate. In each case, the wall is rigid and essentially inorganic. Typical phyla Chromalveolata Chromista Heterokontophyta Haptophyta Cryptophyta (cryptomonads) Alveolata Dinoflagellata Apicomplexa Ciliophora (ciliates) Cabozoa Excavata Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Archaeplastida (in part) Rhodophyta (red algae) Glaucophyta (basal archaeplastids) Amoebozoa Choanozoa Many others; classification varies Protists (IPA: (RP); (GenAm)), Greek protiston -a meaning the (most) first of all... For the programming language, see algae (programming language). ... Orders Centrales Pennales Diatoms (Greek: (dia) = through + (temnein) = to cut, i. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... Classes Polycystinea Acantharea Sticholonchea Radiolarians (also radiolaria) are amoeboid protozoa that produce intricate mineral skeletons, typically with a central capsule dividing the cell into inner and outer portions, called endoplasm and ectoplasm. ... Divisions Chlorophyta Charophyta Green algae are microscopic protists; found in all aquatic environments, including marine, freshwater and brackish water. ... Orders Dasycladaceae Polyphysaceae In taxonomy, the Dasycladales is an order of large unicellular green algae under the class Ulvophyceae. ... Calcium carbonate is a chemical compound, with the chemical formula CaCO3. ...


Permeability

The primary cell wall of most plant cells is semi-permeable and permit the passage of small molecules and small proteins, with size exclusion estimated to be 30-60 kDa. Key nutrients, especially water and carbon dioxide, are distributed throughout the plant from cell wall to cell wall in apoplastic flow. Plant cell structure Plant cells are eukaryotic cells that differ in several key respects from the cells of other eukaryotic organisms. ... Scheme of semipermeable membrane during hemodialysis, where red is blood, blue is the dialysing fluid, and yellow is the membrane. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Within a plant, the apoplast is the free diffusional space outside the plasma membrane. ...


Plant cell walls

Composition

Molecular structure of the primary cell wall in plants.
Molecular structure of the primary cell wall in plants.

The major carbohydrates making up the primary (growing) cell wall are cellulose, hemicellulose and pectin. The cellulose microfibrils are linked via hemicellulosic tethers to form the cellulose-hemicellulose network, which is embedded in the pectin matrix. The most common hemicellulose in the primary cell wall is xyloglucan. In grass cell walls, xyloglucan and pectin are reduced in abundance and partially replaced by glucuronarabinoxylan, a hemicellulose. Primary cell walls characteristically extend (grow) by a mechanism called acid growth, which involves turgor-driven movement of the strong cellulose microfibrils within the weaker hemicellulose/pectin matrix, catalyzed by expansin proteins. Image File history File links Plant_cell_wall_diagram. ... Image File history File links Plant_cell_wall_diagram. ... Lactose is a disaccharide found in milk. ... Cellulose as polymer of β-D-glucose Cellulose in 3D Cellulose (C6H10O5)n is a polysaccharide of beta-glucose. ... A hemicellulose can be any of several heteropolymers (matrix polysaccharides) present in almost all cell walls along with cellulose. ... Pectin, a white to light brown powder, is a heterosaccharide derived from the cell wall of higher terrestrial plants. ... The microfibril is a very fine fibril, or fiber-like strand, consisting of glycoproteins. ... Xyloglucan is the main hemicellulose in the primary cell wall of dicotyledonous plants. ... Acid growth refers to the ability of plant cells to quickly stretch. ... Turgor (also called turgor pressure or osmotic pressure) is the pressure that can build in a space that is enclosed by a membrane that is permeable to a solvent of a solution such as water but not to the solutes of the soluton. ...


The major polymers that make up wood (largely secondary cell walls) include cellulose (35 to 50%), xylan, a type of hemicellulose, (20 to 35%) and a complex phenolic polymer called lignin (10 to 25%). Lignin penetrates the spaces in the cell wall between cellulose, hemicellulose and pectin components, driving out water and strengthening the wall. Secondary walls - especially in grasses - may also contain microscopic silicate crystals, which may strengthen the wall and protect it from herbivores. A polymer (from Greek: πολυ, polu, many; and μέρος, meros, part) is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ... Xylan Corporation was a start-up company founded by Steve Kim. ... Lignin (sometimes lignen) is a chemical compound (complex, highly cross-linked aromatic polymer) that is most commonly derived from wood and is an integral part of the cell walls of plants, especially in tracheids, xylem fibres and sclereids. ...


Plant cells walls also contain numerous enzymes, such as hydrolases, esterases, peroxidases, and transglycosylases, that cut, trim and cross link wall polymers. Small amounts (1-5%) of structural proteins are found in most plant cell walls; they are classified as hydroxyproline-rich glycoproteins (HRGP), arabinogalactan proteins (AGP), glycine-rich proteins (GRPs), and proline-rich proteins (PRPs). Each class of glycoprotein is defined by a characteristic, highly repetitive protein sequence. Most are glycosylated, contain hydroxyproline (Hyp) and become cross-linked in the cell wall. These proteins are often concentrated in specialized cells and in cell corners. Cell walls of the epidermis and endodermis may also contain suberin or cutin, two polyester-like polymers that protect the cell from herbivores.[2] The relative composition of carbohydrates, secondary compounds and protein varies between plants and between the cell type and age. A representation of the 3D structure of myoglobin showing coloured alpha helices. ... Glycosylation is the process or result of addition of saccharides to proteins and lipids. ... Structure of hydroxyproline 4-Hydroxyproline, or hydroxyproline (C5H9O3N), is an uncommon amino acid, abbreviated as HYP, e. ... Cross-section of a flax plant stem: 1. ... Endodermis is the bottom layer of skin. ... Suberin is a waxy substance found in higher plants. ... Cutin is a waxy substance which is a component of cuticle at the surface of leaves in plants. ...


Up to three strata or layers may be found in plant cell walls:[3]

  • The middle lamella, a layer rich in pectins. This outermost layer forming the interface between adjacent plant cells and glues them together.
  • The primary cell wall, generally a thin, flexible and extensible layer formed while the cell is growing.
  • The secondary cell wall, a thick layer formed inside the primary cell wall after the cell is fully grown. It is not found in all cell types. In some cells, such as found xylem, the secondary wall contains lignin, which strengthens and waterpoofs the wall.

Cell walls in some plant tissues also function as storage depots for carbohydrates that can be broken down and resorbed to supply the metabolic and growth needs of the plant. For example, endosperm cell walls in the seeds of cereal grasses, nasturtium, and other species, are rich in glucans and other polysaccharides that are readily digested by enzymes during seed germination to form simple sugars that nourish the growing embryo. Cellulose microfibrils are not readily digested by plants, however. Pectin, a white to light brown powder, is a heterosaccharide derived from the cell wall of higher terrestrial plants. ... In vascular plants, xylem is one of the two types of transport tissue, phloem being the other one. ... Lignin (sometimes lignen) is a chemical compound (complex, highly cross-linked aromatic polymer) that is most commonly derived from wood and is an integral part of the cell walls of plants, especially in tracheids, xylem fibres and sclereids. ...


Formation

The middle lamella is laid down first, formed from the cell plate during cytokinesis, and the primary cell wall is then deposited inside the middle lamella. The actual structure of the cell wall is not clearly defined and several models exist - the covalently linked cross model, the tether model, the diffuse layer model and the stratified layer model. However, the primary cell wall, can be defined as composed of cellulose microfibrils aligned at all angles. Microfibrils are held together by hydrogen bonds to provide a high tensile strength. The cells are held together and share the gelatinous membrane called the middle lamella, which contains magnesium and calcium pectates (salts of pectic acid). Cells interact though plasmodesma(ta), which are inter-connecting channels of cytoplasm that connect to the protoplasts of adjacent cells across the cell wall. A cell that has almost completed cytokinesis. ... General Name, symbol, number magnesium, Mg, 12 Chemical series alkaline earth metals Group, period, block 2, 3, s Appearance silvery white solid at room temp Standard atomic weight 24. ... For other uses, see Calcium (disambiguation). ... A cell wall is a fairly rigid layer surrounding a cell located outside of the plasma membrane (also known, in some cases, as the cell membrane) that provides additional support and protection. ... Pectic acid (C17H24O16) is a transparent and gelatinous acid existing in ripe fruit and some forms of vegetable. ... Plasmodesmata (Singular, plasmodesma) are small cell junctions in a plant cell which connect the cytoplasm of adjacent plant cells, forming a circulatory and communication system connecting the cells in plant tissue. ...


In some plants and cell types, after a maximum size or point in development has been reached, a secondary wall is constructed between the plant cell and primary wall. Unlike the primary wall, the microfibrils are aligned mostly in the same direction, and with each additional layer the orientation changes slightly. Cells with secondary cell walls are rigid. Cell to cell communication is possible through pits in the secondary cell wall that allow plasmodesma to connect cells through the secondary cell walls.


Trees modify cell walls in their branches to reinforce and support structure.[4] Conifers, such as pine, produce thicker cell walls on the undersides of branches to push their branches upwards. The resulting wood is called compression wood. By contrast, hardwood trees reinforce the walls on the upper sides of branches to pull their branches up. This is known as tension wood. Additional thickening may occur in other parts of the plant in response to mechanical stress. It has been suggested that this article or section be merged with Tree (disambiguation). ... Orders & Families Cordaitales † Pinales   Pinaceae - Pine family   Araucariaceae - Araucaria family   Podocarpaceae - Yellow-wood family   Sciadopityaceae - Umbrella-pine family   Cupressaceae - Cypress family   Cephalotaxaceae - Plum-yew family   Taxaceae - Yew family Vojnovskyales † Voltziales † The conifers, division Pinophyta, are one of 13 or 14 division level taxa within the Kingdom Plantae. ... Subgenera Subgenus Strobus Subgenus Ducampopinus Subgenus Pinus See Pinus classification for complete taxonomy to species level. ... Reaction wood is formed in response to mechanical stress, and helps to position newly formed parts of the plant in an optimal position. ... Beech is a typical temperate zone hardwood For the record label, see Hardwood Records. ... Reaction wood is formed in response to mechanical stress, and helps to position newly formed parts of the plant in an optimal position. ... Reaction wood is formed in response to mechanical stress, and helps to position newly formed parts of the plant in an optimal position. ...


Algal cell walls

Scanning electron micrographs of diatoms showing the external appearance of the cell wall
Scanning electron micrographs of diatoms showing the external appearance of the cell wall

Like plants, algae have cell walls.[5] Algal cell walls contain cellulose and a variety of glycoproteins. The inclusion of additional polysaccharides in algal cells walls is used as a feature for algal taxonomy. Image File history File links Size of this preview: 734 × 600 pixel Image in higher resolution (1400 × 1144 pixel, file size: 951 KB, MIME type: image/png) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Cell wall ... Image File history File links Size of this preview: 734 × 600 pixel Image in higher resolution (1400 × 1144 pixel, file size: 951 KB, MIME type: image/png) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Cell wall ... SEM Cambridge S150 at Geological Institute, University Kiel, 1980 SEM opened sample chamber The scanning electron microscope (SEM) is a type of electron microscope capable of producing high-resolution images of a sample surface. ... A micrograph is a photograph or similar image taken through a microscope or similar device to show a magnified image of an item. ... Orders Centrales Pennales Diatoms (Greek: (dia) = through + (temnein) = to cut, i. ... N-linked protein glycosylation (N-glycosylation of N-glycans) at Asn residues (Asn-x-Ser/Thr motifs) in glycoproteins[1]. Glycoproteins are proteins that contain oligosaccharide chains (glycans) covalently attached to their polypeptide backbones. ... Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ...

  • Manosyl form microfibrils in the cell walls of a number of marine green algae including those from the genera, Codium, Dasycladus, and Acetabularia as well as in the walls of some red algae, like Porphyra and Bangia.
  • Xylanes
  • Alginic acid is a common polysaccharide in the cell walls of brown algae
  • Sulfonated polysaccharides occur in the cell walls of most algae; those common in red algae include agarose, carrageenan, porphyran, furcelleran and funoran.

Other compounds that may accumulate in algal cell walls include sporopollenin and calcium ions. Divisions Chlorophyta Charophyta Green algae are microscopic protists; found in all aquatic environments, including marine, freshwater and brackish water. ... Possible classes Florideophyceae Bangiophyceae Cyanidiophyceae The red algae (Rhodophyta, IPA: , from Greek: (rhodon) = rose + (phyton) = plant, thus red plant) are a large group, about 5,000–6,000 species [1] of mostly multicellular, marine algae, including many notable seaweeds. ... Alginic acid (algine, alginate) is a viscous gum that is abundant in the cell walls of brown algae. ... The Heterokontophyta (Phaeophyta or brown algae, singular: brown alga) is a large group of mostly marine multicellular algae, including many seaweeds of colder Northern Hemisphere waters. ... An agarose is a polysaccharide polymer material, generally extracted from seaweed. ... Carrageenans or carrageenins (pronounced ) are a family of linear sulphated polysaccharides extracted from red seaweeds. ... Categories: Stub ... For other uses, see Calcium (disambiguation). ...


The group of algae known as the diatoms synthesize their cell walls (also known as frustules or valves) from silicic acid (specifically orthosilicic acid, H4SiO4). The acid is polymerised intra-cellularly, then the wall is extruded to protect the cell. Significantly, relative to the organic cell walls produced by other groups, silica frustules require less energy to synthesize (approximately 8%), potentially a major saving on the overall cell energy budget[6] and possibly an explanation for higher growth rates in diatoms.[7] For the programming language, see algae (programming language). ... Orders Centrales Pennales Diatoms (Greek: (dia) = through + (temnein) = to cut, i. ... Silicic acid is a general name for a family of chemical compounds of silicon, hydrogen, and oxygen, with the general formula [SiOx(OH)4-2x]n. ... A polymer (from Greek: πολυ, polu, many; and μέρος, meros, part) is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ...


Fungal cell walls

Chemical structure of a unit from a chitin polymer chain.
Chemical structure of a unit from a chitin polymer chain.

There are several groups of organisms that may be called "fungi". Some of these groups have been transferred out of the Kingdom Fungi, in part because of fundamental biochemical differences in the composition of the cell wall. Most true fungi have a cell wall consisting largely of chitin and other polysaccharides.[8] True fungi do not have cellulose in their cell walls, but some fungus-like organisms do. Image File history File links Chitin. ... Image File history File links Chitin. ... Structure of the chitin molecule, showing two of the N-Acetylglucosamine units that repeat to form long chains in beta-1,4 linkage. ... Structure of the chitin molecule, showing two of the N-Acetylglucosamine units that repeat to form long chains in beta-1,4 linkage. ... Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ... Cellulose as polymer of β-D-glucose Cellulose in 3D Cellulose (C6H10O5)n is a polysaccharide of beta-glucose. ...


True fungi

Not all species of fungi have cell walls but in those that do, the plasma membrane is followed by three layers of cell wall material. From inside out these are: Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus) are a large group of organisms ranked as a kingdom within the Domain Eukaryota. ... Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ...

Structure of the chitin molecule, showing two of the N-Acetylglucosamine units that repeat to form long chains in beta-1,4 linkage. ... A polymer (from Greek: πολυ, polu, many; and μέρος, meros, part) is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ... N-Acetylglucosamine (N-Acetyl-D-Glucosamine, or GlcNAc, or NAG) is a monosaccharide derivative of glucose. ... A glucan molecule is a polysaccharide of D-glucose monomers linked by glycosidic bonds. ... D and L forms Haworth projection of mannose in its α-D-mannopyranose form. ... A glycoprotein is a macromolecule composed of a protein and a carbohydrate (a sugar). ... = chemically linked to glucose Source: http://www. ...

Fungus-like protists

The group Oomycetes, also known as water molds, are saprotrophic plant pathogens like fungi. Until recently they were widely believed to be fungi, but structural and molecular evidence[9] has led to their reclassification as heterokonts, related to autotrophic brown algae and diatoms. Unlike fungi, oomycetes typically possess cell walls of cellulose and glucans rather than chitin, although some genera (such as Achlya and Saprolegnia) do have chitin in their walls.[10] The fraction of cellulose in the walls is no more than 4 to 20%, far less than the fraction comprised by glucans.[10] Oomycete cell walls also contain the amino acid hydroxyproline, which is not found in fungal cell walls. Orders Lagenidiales Leptomitales Peronosporales Pythiales Rhipidiales Saprolegniales Sclerosporales Water moulds or Oomycetes are a group of filamentous protists, physically resembling fungi. ... A Saprotroph (or saprobe) is an organism that obtains its nutrients from non-living organic matter, usually dead and decaying plant or animal matter, by absorbing soluble organic compounds. ... Phytopathology or Plant Pathology is the science of diagnosing and managing plant diseases. ... In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is separately enclosed within its own lipid membrane. ... Molecular biology is the study of biology at a molecular level. ... Typical classes Colored groups Chrysophyceae (golden algae) Synurophyceae Actinochrysophyceae (axodines) Pelagophyceae Phaeothamniophyceae Bacillariophyceae (diatoms) Bolidophyceae Raphidophyceae Eustigmatophyceae Xanthophyceae (yellow-green algae) Phaeophyceae (brown algae) Colorless groups Oomycetes (water moulds) Hypochytridiomycetes Bicosoecea Labyrinthulomycetes (slime nets) Opalinea Proteromonadea The heterokonts or stramenopiles are a major line of eukaryotes containing about 10,500... Green (from chlorophyll) fronds of a maidenhair fern: a photoautotroph Flowchart to determine if a species is autotroph, heterotroph, or a subtype An autotroph (from the Greek autos = self and trophe = nutrition) is an organism that produces complex organic compounds from simple inorganic molecules and an external source of energy... The Heterokontophyta (Phaeophyta or brown algae, singular: brown alga) is a large group of mostly marine multicellular algae, including many seaweeds of colder Northern Hemisphere waters. ... Orders Centrales Pennales Diatoms (Greek: (dia) = through + (temnein) = to cut, i. ... A glucan molecule is a polysaccharide of D-glucose monomers linked by glycosidic bonds. ... Species Achlya ambisexualis Achlya conspicua Achlya klebsiana Achlya is a genus of freshwater mould. ... Species Saprolegnia is a genus of freshwater mould. ... This article is about the class of chemicals. ... Structure of hydroxyproline 4-Hydroxyproline, or hydroxyproline (C5H9O3N), is an uncommon amino acid, abbreviated as HYP, e. ...


The dictyostelids are another group formerly classified among the fungi. They are slime moulds that feed as unicellular amoebae, but aggregate into a reproductive stalk and sporangium under certain conditions. Cells of the reproductive stalk, as well as the spores formed at the apex, possess a cellulose wall.[11] The spore wall has been shown to possess three layers, the middle of which is composed primarily of cellulose, and the innermost is sensitive to cellulase and pronase.[11] Families & Genera Dictyosteliidae     Dictyostelium     Polysphondylium     Coenonia Actyosteliidae     Acytostelium The dictyostelids are a group of cellular slime moulds. ... Typical orders Protostelia Protosteliida Myxogastria Liceida Echinosteliida Trichiida Stemonitida Physarida Dictyostelia Dictyosteliida Slime (or slime mold) is a broad term often referring to roughly six groups of Eukaryotes. ... For other uses, see Amoeba (disambiguation). ... A sporangium (pl. ... This article or section is in need of attention from an expert on the subject. ... Cellulose as polymer of β-D-glucose Cellulose in 3D Cellulose (C6H10O5)n is a polysaccharide of beta-glucose. ... Cellulase is an enzyme complex which breaks down cellulose to beta-glucose. ... Pronase is a serine protease found in Streptomyces griseus. ...


Prokaryotic cell walls

Bacterial cell walls

Diagram of a typical gram-negative bacterium, with the thin cell wall sandwiched between the yellow outer membrane and the thin red plasma membrane
Diagram of a typical gram-negative bacterium, with the thin cell wall sandwiched between the yellow outer membrane and the thin red plasma membrane
Schematic of typical gram-positive cell wall showing arrangement of N-Acetylglucosamine and N-Acetlymuramic acid
Schematic of typical gram-positive cell wall showing arrangement of N-Acetylglucosamine and N-Acetlymuramic acid
Further information: Cell envelope

Around the outside of the cell membrane is the bacterial cell wall. Bacterial cell walls are made of peptidoglycan (also called murein), which is made from polysaccharide chains cross-linked by unusual peptides containing D-amino acids.[12] Bacterial cell walls are different from the cell walls of plants and fungi which are made of cellulose and chitin, respectively.[13] The cell wall of bacteria is also distinct from that of Archaea, which do not contain peptidoglycan. The cell wall is essential to the survival of many bacteria. The antibiotic penicillin is able to kill bacteria by inhibiting a step in the synthesis of peptidoglycan.[13] Bacteria that are Gram-negative are not stained dark blue or violet by Gram staining, in contrast to Gram-positive bacteria. ... Gram-positive bacteria are those that are stained dark blue or violet by gram staining, in contrast to gram-negative bacteria, which are not affected by the stain. ... The cell envelope is the cell membrane and cell wall plus an outer membrane, if one is present. ... Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of eubacteria. ... Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ... Peptides (from the Greek πεπτος, digestible), are the family of short molecules formed from the linking, in a defined order, of various α-amino acids. ... This article is about the class of chemicals. ... u fuck in ua ... Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus) are a large group of organisms ranked as a kingdom within the Domain Eukaryota. ... Cellulose as polymer of β-D-glucose Cellulose in 3D Cellulose (C6H10O5)n is a polysaccharide of beta-glucose. ... Structure of the chitin molecule, showing two of the N-Acetylglucosamine units that repeat to form long chains in beta-1,4 linkage. ... Penicillin core structure Penicillin (abbreviated PCN) is a group of β-lactam antibiotics used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms. ...


There are broadly speaking two different types of cell wall in bacteria, called Gram-positive and Gram-negative. The names originate from the reaction of cells to the Gram stain, a test long-employed for the classification of bacterial species.[14] Gram-positive bacteria are those that are stained dark blue or violet by gram staining, in contrast to gram-negative bacteria, which are not affected by the stain. ... Bacteria that are Gram-negative are not stained dark blue or violet by Gram staining, in contrast to Gram-positive bacteria. ... Gram staining is a method for staining samples of bacteria that differentiates between the two main types of bacterial cell wall. ...


Gram-positive bacteria possess a thick cell wall containing many layers of peptidoglycan and teichoic acids. In contrast, Gram-negative bacteria have a relatively thin cell wall consisting of a few layers of peptidoglycan surrounded by a second lipid membrane containing lipopolysaccharides and lipoproteins. Most bacteria have the Gram-negative cell wall and only the Firmicutes and Actinobacteria (previously known as the low G+C and high G+C Gram-positive bacteria, respectively) have the alternative Gram-positive arrangement.[15] These differences in structure can produce differences in antibiotic susceptibility, for instance vancomycin can kill only Gram-positive bacteria and is ineffective against Gram-negative pathogens, such as Haemophilus influenzae or Pseudomonas aeruginosa.[16] Teichoic acids are polymers of glycerol or ribitol linked via phosphodiester bonds. ... Lipopolysaccharide (captions are in French) Lipopolysaccharide (LPS) is a large molecule consisting of a lipid and a polysaccharide (carbohydrate) joined by a covalent bond. ... A lipoprotein is a biochemical assembly that contains both proteins and lipids. ... Classes Bacilli Clostridia Mollicutes The Firmicutes are a division of bacteria, most of which have Gram-positive cell wall structure. ... Subclasses Acidimicrobidae Actinobacteridae Coriobacteridae Rubrobacteridae Sphaerobacteridae The Actinobacteria or Actinomycetes are a group of Gram-positive bacteria. ... Crystal structure of a short peptide L-Lys-D-Ala-D-Ala (bacterial cell wall precursor, in green) bound to vancomycin (blue) through hydrogen bonds. ... Binomial name Haemophilus influenzae (Lehmann & Neumann 1896) Winslow 1917 Haemophilus influenzae, formerly called Pfeiffers bacillus or Bacillus influenzae, is a non-motile Gram-negative coccobacillus first described in 1892 by Dr. Richard Pfeiffer during an influenza pandemic. ... Binomial name Pseudomonas aeruginosa (Schroeter 1872) Migula 1900 Synonyms Bacterium aeruginosum Schroeter 1872 Bacterium aeruginosum Cohn 1872 Micrococcus pyocyaneus Zopf 1884 Bacillus aeruginosus (Schroeter 1872) Trevisan 1885 Bacillus pyocyaneus (Zopf 1884) Flügge 1886 Pseudomonas pyocyanea (Zopf 1884) Migula 1895 Bacterium pyocyaneum (Zopf 1884) Lehmann and Neumann 1896 Pseudomonas polycolor...


Archaeal cell walls

Although not truly unique, the cell walls of Archaea are unusual. Whereas peptidoglycan is a standard component of all bacterial cell walls, all archaeal cell walls lack peptidoglycan,[17] with the exception of one group of methanogens.[1] In that group, the peptidoglycan is a modified form very different from the kind found in bacteria.[17] There are four types of cell wall currently known among the Archaea. Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (pronounced ) are a group of prokaryotic and single-celled microorganisms. ... Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of eubacteria. ... Methanogens are archaea that produce methane as a metabolic byproduct in anoxic conditions. ...


One type of archaeal cell wall is that composed of pseudopeptidoglycan (also called pseudomurein). This type of wall is found in some methanogens, such as Methanobacterium and Methanothermus.[18] While the overall structure of archaeal pseudopeptidoglycan superficially resembles that of bacterial peptidoglycan, there are a number of significant chemical differences. Like the peptidoglycan found in bacterial cell walls, pseudopeptidoglycan consists of polymer chains of glycan cross-linked by short peptide connections. However, unlike peptidoglycan, the sugar N-acetylmuramic acid is replaced by N-acetyltalosaminuronic acid,[17] and the two sugars are bonded with a β,1-3 glycosidic linkage instead of β,1-4. Additionally, the cross-linking peptides are L-amino acids rather than D-amino acids as they are in bacteria.[18] Pseudomurein (also known as pseudopeptidoglycan) is a major cell wall component of some archaebacteria that chemically differs from but morphologically, functionally, and structurally resembles eubacterial peptidoglycan. ... Methanogens are archaea that produce methane as a metabolic byproduct in anoxic conditions. ... Species Synonyms Methanobacterium Kluyver and van Niel 1936 In taxonomy, Methanobacterium is a genus of the Methanobacteriaceae. ... Species Synonyms In taxonomy, Methanothermus is a genus of the Methanothermaceae. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... A polymer (from Greek: πολυ, polu, many; and μέρος, meros, part) is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ... Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ... Peptides (from the Greek πεπτος, digestible), are the family of short molecules formed from the linking, in a defined order, of various α-amino acids. ... N-Acetylmuramic acid, or MurNAc, is the ether of lactic acid and N-acetylglucosamine with a chemical formula of C11H19NO8. ... N-Acetyltalosaminuronic acid is a uronic acid. ... This article is about the class of chemicals. ...


A second type of archaeal cell wall is found in Methanosarcina and Halococcus. This type of cell wall is composed entirely of a thick layer of polysaccharides, which may be sulfated in the case of Halococcus.[18] Structure in this type of wall is complex and as yet is not fully investigated. Species M. acetivorans Methanosarcina are the only known anaerobic methanogens to produce methane using all three known metabolic pathways for methanogenesis. ... Species Synonyms Halococcus Schoop 1935 In taxonomy, Halococcus is a genus of the Halobacteriaceae. ... Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ... The sulfate anion, SO42− The structure and bonding of the sulfate ion In inorganic chemistry, a sulfate (IUPAC-recommended spelling; also sulphate in British English) is a salt of sulfuric acid. ...


A third type of wall among the Archaea consists of glycoprotein, and occurs in the hyperthermophiles, Halobacterium, and some methanogens. In Halobacterium, the proteins in the wall have a high content of acidic amino acids, giving the wall an overall negative charge. The result is an unstable structure that is stabilized by the presence of large quantities of positive sodium ions that neutralize the charge.[18] Consequently, Halobacterium thrives only under conditions with high salinity. N-linked protein glycosylation (N-glycosylation of N-glycans) at Asn residues (Asn-x-Ser/Thr motifs) in glycoproteins[1]. Glycoproteins are proteins that contain oligosaccharide chains (glycans) covalently attached to their polypeptide backbones. ... Hyperthermophiles produce some of the bright colors of Grand Prismatic Spring, Yellowstone National Park A hyperthermophile is an organism that thrives in extremely hot environments - that is, hotter than around 60°C. The optimal temperatures are between 80°C and 110°C; in fact, the recently-discovered Strain 121 [1... Species H. salinarum Synonyms Halobacter Anderson 1954 Halobacter Halobacterium Elazari-Volcani 1957 not Halobacterium Schoop 1935 (nomen nudum) Note: The word halobacterium is also the singular form of the word halobacteria. In taxonomy, Halobacterium is a genus of the Halobacteriaceae. ... Methanogens are archaea that produce methane as a metabolic byproduct in anoxic conditions. ... A representation of the 3D structure of myoglobin showing coloured alpha helices. ... For other uses, see acid (disambiguation). ... This article is about the class of chemicals. ... For sodium in the diet, see Salt. ... This article is about the electrically charged particle. ... Annual mean sea surface salinity for the World Ocean. ...


In other Archaea, such as Methanomicrobium and Desulfurococcus, the wall may be composed only of surface-layer proteins,[1] known as an S-layer. S-layers are common in bacteria, where they serve as either the sole cell-wall component or an outer layer in conjunction with peptidoglycan and murein. Most Archaea are Gram-negative, though at least one Gram-positive member is known.[1] Species Synonyms Methanomicrobium Balch and Wolfe 1981 In taxonomy, Methanomicrobium is a genus of the Methanomicrobiaceae. ... Species Synonyms Desulfurococcus Zillig and Stetter 1983 In taxonomy, Desulfurococcus is a genus of the Desulfurococcaceae. ... A representation of the 3D structure of myoglobin showing coloured alpha helices. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of eubacteria. ... Murein is a biochemical which is a large constituent of cell walls in prokaryotes. ...


See also

Bacteria, despite their apparent simplicity contain a well developed cell structure which is responsible for many of their unique biological properties. ... Plant cell structure Plant cells are eukaryotic cells that differ in several key respects from the cells of other eukaryotic organisms. ...

References

  1. ^ a b c d Howland, John L. (2000). The Surprising Archaea: Discovering Another Domain of Life. Oxford: Oxford University Press, 69-71. ISBN 0-19-511183-4. 
  2. ^ Laurence Moire, Alain Schmutz, Antony Buchala, Bin Yan, Ruth E. Stark, and Ulrich Ryser (1999). "Glycerol Is a Suberin Monomer. New Experimental Evidence for an Old Hypothesis". Plant Physiol. 119: 1137-1146
  3. ^ Buchanan; Gruissem, Jones (2000). Biochemistry & molecular biology of plants, 1st ed., American society of plant physiology. ISBN 0-943088-39-9. 
  4. ^ Wilson, Brayton F. (1984). The Growing Tree, revised ed., Amherst: University of Massachusetts Press, 114-115. ISBN 0-87023-424-2. 
  5. ^ Sendbusch, Peter V. (2003-07-31). "Cell Walls of Algae". Botany Online. Retrieved on 2007-10-29.
  6. ^ Raven, J. A. (1983). The transport and function of silicon in plants. Biol. Rev. 58, 179-207.
  7. ^ Furnas, M. J. (1990). "In situ growth rates of marine phytoplankton : Approaches to measurement, community and species growth rates". J. Plankton Res. 12, 1117-1151.
  8. ^ Hudler, George W. (1998). Magical Mushrooms, Mischievous Molds. Princeton, NJ: Princeton University Press, 7. ISBN 0-691-02873-7.
  9. ^ Sengbusch, Peter V. (2003-07-31). "Interactions between Plants and Fungi: the Evolution of their Parasitic and Symbiotic Relations". biologie.uni-hamburg.de. Retrieved on 2007-10-29.
  10. ^ a b Alexopoulos, C. J., C. W. Mims, & M. Blackwell (1996). Introductory Mycology 4. New York: John Wiley & Sons, 687-688. ISBN 0-471-52229-5.
  11. ^ a b Raper, Kenneth B. (1984). The Dictyostelids. Princeton, NJ: Princeton University Press, 99-100. ISBN 0-691-08345-2.
  12. ^ van Heijenoort J (2001). "Formation of the glycan chains in the synthesis of bacterial peptidoglycan". Glycobiology 11 (3): 25R – 36R. doi:10.1093/glycob/11.3.25R. PMID 11320055. 
  13. ^ a b Koch A (2003). "Bacterial wall as target for attack: past, present, and future research". Clin Microbiol Rev 16 (4): 673 – 87. doi:10.1128/CMR.16.4.673-687.2003. PMID 14557293. 
  14. ^ Gram, HC (1884). "Über die isolierte Färbung der Schizomyceten in Schnitt- und Trockenpräparaten". Fortschr. Med. 2: 185–189. 
  15. ^ Hugenholtz P (2002). "Exploring prokaryotic diversity in the genomic era". Genome Biol 3 (2): REVIEWS0003. doi:10.1186/1471-2148-1-8. PMID 11864374. 
  16. ^ Walsh F, Amyes S (2004). "Microbiology and drug resistance mechanisms of fully resistant pathogens.". Curr Opin Microbiol 7 (5): 439-44. doi:10.1016/j.mib.2004.08.007. PMID 15451497. 
  17. ^ a b c White, David. (1995) The Physiology and Biochemistry of Prokaryotes, pages 6, 12-21. (Oxford: Oxford University Press). ISBN 0-19-508439-X.
  18. ^ a b c d Brock, Thomas D., Michael T. Madigan, John M. Martinko, & Jack Parker. (1994) Biology of Microorganisms, 7th ed., pages 818-819, 824 (Englewood Cliffs, NJ: Prentice Hall). ISBN 0-13-042169-3.

Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... is the 212th day of the year (213th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 302nd day of the year (303rd in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... is the 212th day of the year (213th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 302nd day of the year (303rd in leap years) in the Gregorian calendar. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... For other uses of Gram, see Gram (disambiguation). ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...

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In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is separately enclosed within its own lipid membrane. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... In spermatozoa of many animals, the acrosome is an organelle that develops over the anterior half of the spermatozoons head. ... The cell membrane (also called the plasma membrane, plasmalemma or phospholipid bilayer) is a selectively permeable lipid bilayer found in all cells. ... A centriole showing the nine triplets of microtubules. ... Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. ... Not to be confused with Psyllium. ... For the insect anatomical structure, see Antenna (biology). ... In cell biology, the centrosome is the main microtubule organizing center (MTOC) of the animal cell as well as a regulator of cell-cycle progression. ... Schematic showing the cytoplasm, with major components of a typical animal cell. ... The endoplasmic reticulum or ER is an organelle found in all eukaryotic cells that is an interconnected network of tubules, vesicles and cisternae that is responsible for several specialized functions: Protein translation, folding, and transport of proteins to be used in the cell membrane (e. ... In biology an endosome is a membrane-bound compartment inside cells. ... Micrograph of Golgi apparatus, visible as a stack of semicircular black rings near the bottom. ... Various organelles labeled. ... In a biological cell, a melanosome is an organelle containing melanin, the most common light-absorbing pigment found in the animal kingdom. ... Electron micrograph of a mitochondrion showing its mitochondrial matrix and membranes In cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed organelle that is found in most eukaryotic cells. ... A diagram of the structure of a Myofybril Myofibrils (obsolete term: sarcostyles) are cylindrical organelles, found within muscle cells. ... HeLa cells stained for DNA with the Blue Hoechst dye. ... The nucleolus is contained within the cell nucleus. ... Parenthesomes are found in basidiomycete fungus. ... Basic structure of a peroxisome Peroxisomes are ubiquitous organelles in eukaryotes that participate in the metabolism of fatty acids and other metabolites. ... Plant cells with visible chloroplasts. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ... Schematic of typical animal cell, showing subcellular components: (1) nucleolus (2) nucleus (3) ribosome (4) vesicle (5) rough endoplasmic reticulum (ER) (6) Golgi apparatus (7) Cytoskeleton (8) smooth ER (9) mitochondria (10) vacuole (11) cytoplasm (12) lysosome (13) centrioles Vacuoles are found in the cytoplasm of most plant cells and... In cell biology, a vesicle is a relatively small and enclosed compartment, separated from the cytosol by at least one lipid bilayer. ... Pinguicula grandiflora commonly known as a Butterwort Example of a cross section of a stem [1] Botany is the scientific study of plant life. ... Ethnobotany is the study of the relationship between plants and people: Fromethno - study of people and botany - study of plants. ... 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Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants or angiosperms are the most widespread group of land plants. ... For other uses, see Flower (disambiguation). ... For other uses, see Fruit (disambiguation). ... Look up foliage in Wiktionary, the free dictionary. ... Tunica-Corpus model of the apical meristem. ... For other uses, see Root (disambiguation). ... Stem showing internode and nodes plus leaf petiole and new stem rising from node. ... Stoma of a leaf under a microscope. ... Cross section of celery stalk, showing vascular bundles, which include both phloem and xylem. ... For other uses, see Wood (disambiguation). ... Plant cell structure Plant cells are eukaryotic cells that differ in several key respects from the cells of other eukaryotic organisms. ... Chlorophyll is a green pigment found in most plants, algae, and cyanobacteria. ... Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. ... 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SEM image of pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomoea purpurea), prairie hollyhock (Sidalcea malviflora), oriental lily (Lilium auratum), evening primrose (Oenothera fruticosa), and castor bean (Ricinus communis). ... Carpenter bee with pollen collected from Night-blooming cereus Pollination is an important step in the reproduction of seed plants: the transfer of pollen grains (containing the male gametes, sperm) to the plant carpel of flowering plants, the structure that contains the ovule (which in turn houses the female gamete... A ripe red jalapeño cut open to show the seeds For other uses, see Seed (disambiguation). ... This article or section is in need of attention from an expert on the subject. ... Young sporophytes of the common moss Tortula muralis. ... Plant taxonomy is the science that finds, describes, classifies and names plants. ... A botanical name is a formal name conforming to the ICBN. As with its zoological and bacterial equivalents it may also be called a scientific name. Botanical names may be in one part (genus and above), two parts (species) or three parts (below the rank of species). ... Botanical nomenclature Plants are given formal names, governed by the ICBN. Within the limits set by the ICBN there is a separate set of rules, the ICNCP, for those plants in cultivation that require separate recognition, so-called cultivars. ... Studying a plant sample in the Herbarium In botany, a herbarium is a collection of preserved plant specimens. ... The International Association for Plant Taxonomy (IAPT) is devoted to plant systematics, taxonomy and nomenclature. ... The International Code of Botanical Nomenclature (ICBN) is the set of rules that governs plant nomenclature, i. ... Writing the Species Plantarum was one of Carolus Linnaeus two great contributions to the Scientific community. ...

  Results from FactBites:
 
Cell wall - Wikipedia, the free encyclopedia (1012 words)
Cells interact though plasmodesma(ta), which are inter-connecting channels of cytoplasm that connect to the protoplasts of adjacent cells across the cell wall.
Cell walls of bacteria are primarily used for protection against hostile environments or, in the case of pathogenic bacteria, against the immune system of the host.
The cell walls of bacteria are also vital for containing the high osmotic pressure inside bacterial cells caused by the high concentration of solutes in the cytoplasm.
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