Prokaryotic bacteria cell structure

Prokaryotes (IPA: /prəʊˈkæriəʊtiz/) are a group of organisms that lack a cell nucleus (= karyon), or any other membrane-bound organelles. Most are unicellular, but some prokaryotes are multicellular organisms. The word prokaryotes comes from the Old Greek pro- before + karyon nut or kernel, referring to the cell nucleus, + suffix -otos, pl. -otes; it is also spelled "procaryotes".^[1] Image File history File links Prokaryote_cell_diagram. ... Image File history File links Prokaryote_cell_diagram. ... IPA may refer to: The International Phonetic Alphabet or India Pale Ale ... HeLa cells stained for DNA with the Blue Hoechst dye. ... A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ... The Greek language (Greek Ελληνικά, IPA // – Hellenic) is an Indo-European language with a documented history of some 3,000 years. ... For other uses, see Nut (disambiguation). ... Look up Kernel in Wiktionary, the free dictionary. ... It has been suggested that Ending (linguistics) be merged into this article or section. ... Look up plural in Wiktionary, the free dictionary. ...

The prokaryotes are divided into two domains: the bacteria and the archaea. Archaea or Archaebacteria are a newly appointed kingdom of life. These organisms were originally thought to live only in inhospitable conditions such as extremes of temperature, pH, and radiation, but have since been found in all types of habitats. 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 (), or archaebacteria, are a major group of microorganisms. ... Ernst Haeckels presentation of a three-kingdom system (Plantae, Protista, Animalia) in his 1866 Generelle Morphologie der Organismen). ... Look up habitat in Wiktionary, the free dictionary. ...

Relationship to Eukaryotes

A distinction between prokaryotes and eukaryotes (meaning true kernel, also spelled "eucaryotes") is that eukaryotes do have "true" nuclei containing their DNA, whereas the genetic material in prokaryotes is not membrane-bound. Eukaryotic organisms, such as humans, may be unicellular or multicellular. The difference between the structure of prokaryotes and eukaryotes is so great that it is considered to be the most important distinction among groups of organisms. Most prokaryotes are bacteria, and the two terms are often treated as synonyms. In 1977, Carl Woese proposed dividing prokaryotes into the Bacteria and Archaea (originally Eubacteria and Archaebacteria) because of the significant genetic differences between the two. This arrangement of Eukaryota (also called "Eukarya"), Bacteria, and Archaea is called the three-domain system replacing the traditional two-empire system. A criticism of this classification is that the word "prokaryote" itself is based on what these organisms are not (they are not eukaryotic), rather than what they are (either archea or bacteria). Kingdoms Animalia - Animals Fungi Plantae - Plants Chromalveolata Protista Alternative phylogeny Unikonta Opisthokonta Metazoa Choanozoa Eumycota Amoebozoa Bikonta Apusozoa Cabozoa Rhizaria Excavata Corticata Archaeplastida Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... In biology and ecology, an organism (in Greek organon = instrument) is a living being. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Carl Richard Woese (born July 15, 1928, Syracuse, New York) is an American microbiologist famous for defining the Archaea (a new domain or kingdom of life) in 1977 by phylogenetic taxonomy of 16S ribosomal RNA, a technique pioneered by Woese and which is now standard practice. ... Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (), or archaebacteria, are a major group of microorganisms. ... The three-domain system is a biological classification introduced by Carl Woese in 1990 that emphasizes his separation of prokaryotes into two groups, originally called Eubacteria and Archaebacteria. ... The two-empire system is the top-level biologicial classification system in general use before the establishment of the three-domain system. ...

In light of the two-empire system, the cell structure of prokaryotes differs greatly from eukaryotes. Thus using the three-domain system, the cell structure of archea are to a great extent (and bacteria to some lesser extent) differ from the cell structure of eukaryotes. The defining characteristic is the absence of a nucleus or nuclear envelope. Prokaryotes were also previously considered to lack cytoskeletons and to lack membrane-bound cell compartments such as vacuoles, endoplasmic reticulum/endoplasmic reticula, Golgi apparatus, mitochondria and chloroplasts. In eukaryotes, the latter two perform various metabolic processes and are believed to have been derived from endosymbiotic bacteria. In prokaryotes similar processes occur across the cell membrane; endosymbionts are extremely rare. The cell walls of prokaryotes are generally formed of a different molecule (peptidoglycan) to those of eukaryotes (many eukaryotes do not have a cell wall at all). Both eukaryotes and prokaryotes have structures called ribosomes, which produce protein. Prokaryotes are usually much smaller than eukaryotic cells."^[1] HeLa cells stained for DNA with the Blue Hoechst dye. ... The nuclear envelope (also known as the perinuclear envelope, nuclear membrane, nucleolemma or karyotheca) is the double membrane of the nucleus that encloses genetic material in eukaryotic cells. ... The eukaryotic cytoskeleton. ... Vacuoles are large membrane-bound compartments within some eukaryotic cells where they serve a variety of different functions: capturing food materials or unwanted structural debris surrounding the cell, sequestering materials that might be toxic to the cell, maintaining fluid balance (called turgor) within the cell, exporting unwanted substances from the... 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. ... Micrograph of Golgi apparatus, visible as a stack of semicircular black rings near the bottom. ... 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. ... Chloroplasts are organelles found in plant cells and eukaryotic algae which conduct photosynthesis. ... An endosymbiont (also known as intracellular symbiont) is any organism that lives within cells of another organism, i. ... 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. ...

Prokaryotes also differ from eukaryotes in that they contain only a single loop of stable chromosomal DNA stored in an area named the nucleoid, while eukaryote DNA is found on tightly bound and organized chromosomes. Although some eukaryotes have satellite DNA structures called plasmids, these are generally regarded as a prokaryote feature and many important genes in prokaryotes are stored on plasmids."^[1] The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... It has been suggested that Genophore be merged into this article or section. ... This article is about the biological chromosome. ... Figure 1 : Schematic drawing of a bacterium with plasmids enclosed. ...

Prokaryotes have a larger surface area to volume ratio giving them a higher metabolic rate, a higher growth rate and consequently a shorter generation time compared to Eukaryotes."^[1] Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος(metavallo), the Greek word for change), in the most general sense, is the ingestion and breakdown of complex compounds, coupled...

Genes

Colonies

While prokaryotes are nearly always unicellular, some are capable of forming groups of cells called colonies. Unlike many eukaryotic multicellular organisms, each member of the colony is undifferentiated and capable of free-living (but consider cyanobacteria, a very successful prokaryotic group which does exhibit definite cell differentiation). Individuals that make up such bacterial colonies most often still act independent of one another. Colonies are formed by organisms that remain attached following cell division, sometimes through the help of a secreted slimy layer. A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ... This is a biological article: For a territory administered by another territory see: Colony For a group attempting to affiliate with a Fraternity or Sorority see: Colony (fraternity) In biology, a colony (from Latin colonia) refers to several individual organisms of the same species living closely together, usually for mutual... Orders The taxonomy of the Cyanobacteria is currently under revision. ...

Structure

The sizes of prokaryotes relative to other organisms and biomolecules.

Recent research indicates that all prokaryotes actually do have cytoskeletons albeit more primitive than those of eukaryotes. Besides homologues of actin and tubulin (MreB and FtsZ) the helically arranged building block of flagellum, flagellin is one of the most significant cytoskeletal protein of bacteria as it provides structural backgrounds of chemotaxis, the basic cell physiological response of bacteria. At least some prokaryotes also contain intracellular structures which can be seen as primitive organelles. Membranous organelles (a. k .a. intracellular membranes) are known in some groups of prokaryotes, such as vacuoles or membrane systems devoted to special metabolic properties, e. g. photosynthesis or chemolithotrophy. Additionally, some species also contain protein-enclosed microcompartments mostly associated with special physiological properties (e. .g. carboxysomes or gas vacuoles). Image File history File links Relative_scale. ... Image File history File links Relative_scale. ... The eukaryotic cytoskeleton. ... MreB is a protein found in bacteria that has been identified as a homologue of actin. ... FtsZ is a protein encoded by the ftsZ gene that assembles into a ring at the future site of the septum of bacterial cell division. ... Helicobacter pylori electron micrograph, showing multiple flagella on the cell surface Flagellin is a protein that arranges itself in a hollow cylinder to form the filament in bacterial flagellum. ... Chemotaxis is a kind of taxis, in which bodily cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. ...

For the insect anatomical structure, see Antenna (biology). ... Look up cell membrane in Wiktionary, the free dictionary. ... A cell wall is a fairly rigid layer surrounding a cell, located external to the cell membrane, that provides the cell with structural support, protection, and a filtering mechanism. ... Organelles. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ... It has been suggested that Genophore be merged into this article or section. ... It has been suggested that this article or section be merged with Glycocalix. ... Inclusions (Cytoplasmic) are chemical substances that may or may not be present in a cell, depending on the cell type. ...

Morphology of Prokaryotic cells

Prokaroyotic cells have various shapes, the three basic shapes are.^[2]

• Cocci - spherical
• Bacilli - rod shaped
• Spiral - curve

coccus (plural - cocci) are any spherical or near spherical bacteria. ... Orders Bacillales Lactobacillales The term bacilli (singular bacillus) is used to refer to any rod-shaped bacteria. ... This article does not cite any references or sources. ...

Environment

Prokaryotes are found in nearly all environments on earth. Archaea in particular seem to thrive in harsh conditions, such as high temperatures, thermophiles, or salinity, halophiles. Organisms such as these are referred to as extremophiles. Many prokaryotes live in or on the bodies of other organisms, including humans. Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (), or archaebacteria, are a major group of microorganisms. ... An extremophile is an organism, usually unicellular, which thrives in or requires extreme conditions. ...

Evolution of prokaryotes

It is generally accepted that the first living cells were some form of prokaryote and may have developed out of protobionts. Fossilized prokaryotes approximately 3.5 billion years old have been discovered (less than 1 billion years after the formation of the earth's crust), and prokaryotes are perhaps the most successful and abundant organism even today. Eukaryotes only formed later, from symbiosis of multiple prokaryote ancestors; their first evidence in the fossil record appears approximately 1.7 billion years ago, although genetic evidence suggests they could have formed as early as 3 billion years ago.^[3] This article does not adequately cite its references or sources. ... Protobionts may have been precoursors to prokaryotic cells. ...

While Earth is the only known place in the universe where life exists, some have suggested evidence of life on Mars in the form of fossil or living prokaryotes; this is open to considerable debate and skepticism. An electron microscope reveals bacteria-like structures in meteorite fragment ALH84001 For other uses of Life on Mars, see Life on Mars (disambiguation). ...

Prokaryotes diversified greatly throughout their long existence. The metabolism of prokaryotes is far more varied than that of eukaryotes, leading to many highly distinct types of prokaryotes. For example, in addition to using photosynthesis or organic compounds for energy like eukaryotes do, prokaryotes may obtain energy from inorganic chemicals such as hydrogen sulfide. This has enabled the bacteria to thrive and reproduce. Today, archaebacteria can be found in the cold of Antarctica and in the hot Yellowstone springs. The leaf is the primary site of photosynthesis in plants. ... Hydrogen sulfide (hydrogen sulphide in British English) is the chemical compound with the formula H2S. This colorless, toxic and flammable gas is responsible for the foul odor of rotten eggs and flatulence. ... Phyla / Classes Phylum Crenarchaeota Phylum Euryarchaeota     Halobacteria     Methanobacteria     Methanococci     Methanopyri     Archaeoglobi     Thermoplasmata     Thermococci Phylum Korarchaeota Phylum Nanoarchaeota The Archaea are a major group of prokaryotes. ... Yellowstone National Park is a U.S. National Park located in the states of Idaho, Montana, and Wyoming. ... Green Dragon Spring at Norris Geyser A hot spring is a place where warm or hot groundwater issues from the ground on a regular basis for at least a predictable part of the year, and is significantly above the ambient ground temperature (which is usually around 55~57 F or...

References

1. ^ ^{a b c d} Campbell, N. "Biology:Concepts & Connections". Pearson Education. San Francisco: 2003.
2. ^ Bauman, R. w. "Microbiology". Pearson Education. San Francisco: 2006.
3. ^ Scientific American, October 21, 1999

See also

• Archaea and Bacteria, the two prokaryotic taxa
• Monera, an obsolete kingdom including both of the above
• Bacterial cell structure
• Nanobe
• Virus
• Prion
• Symbiogenesis

Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (), or archaebacteria, are a major group of microorganisms. ... 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. ... Figure 1. ... Ernst Haeckels presentation of a three-kingdom system (Plantae, Protista, Animalia) in his 1866 Generelle Morphologie der Organismen). ... Bacteria, despite their apparent simplicity contain a well developed cell structure which is responsible for many of their unique biological properties. ... A nanobe Nanobes are tiny filamental structures first found in some rocks and sediments. ... This article is about biological infectious particles. ... A prion (IPA: [1] ) — short for proteinaceous infectious particle (-on by analogy to virion) — is a type of infectious agent composed only of protein. ... Symbiogenesis refers to the merging of two separate organisms to form a single new organism. ...

External links

• Prokaryote versus eukaryote, BioMineWiki

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