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Mitochondrion

Two mitochondria from mammalian lung tissue displaying their matrix and membranes as shown by electron microscopy History[edit] The first observations of intracellular structures that probably represent mitochondria were published in the 1840s.[13] Richard Altmann, in 1894, established them as cell organelles and called them "bioblasts".[13] The term "mitochondria" itself was coined by Carl Benda in 1898.[13] Leonor Michaelis discovered that Janus green can be used as a supravital stain for mitochondria in 1900. In 1939, experiments using minced muscle cells demonstrated that one oxygen atom can form two adenosine triphosphate molecules, and, in 1941, the concept of phosphate bonds being a form of energy in cellular metabolism was developed by Fritz Albert Lipmann. The first high-resolution micrographs appeared in 1952, replacing the Janus Green stains as the preferred way of visualising the mitochondria. In 1967, it was discovered that mitochondria contained ribosomes. Structure[edit] Related:  The Biology of LifeOther GMO Research

Qi Etymology[edit] The etymological explanation for the form of the qi logogram (or chi) in the traditional form 氣 is "steam (气) rising from rice (米) as it cooks". The earliest way of writing qi consisted of three wavy lines, used to represent one's breath seen on a cold day. A later version, 气, identical to the present-day simplified character, is a stylized version of those same three lines. For some reason, early writers of Chinese found it desirable to substitute for 气 a cognate character that originally meant to feed other people in a social context such as providing food for guests.[citation needed] Appropriately, that character combined the three-line qi character with the character for rice. Definition[edit] References to concepts analogous to the qi taken to be the life-process or flow of energy that sustains living beings are found in many belief systems, especially in Asia. The ancient Chinese described it as "life force". Pronunciation[edit] Philosophical roots[edit]

Eukaryote Eukaryotes can reproduce both asexually through mitosis and sexually through meiosis and gamete fusion. In mitosis, one cell divides to produce two genetically identical cells. In meiosis, DNA replication is followed by two rounds of cell division to produce four daughter cells each with half the number of chromosomes as the original parent cell (haploid cells). These act as sex cells (gametes – each gamete has just one complement of chromosomes, each a unique mix of the corresponding pair of parental chromosomes) resulting from genetic recombination during meiosis. Cell features[edit] Eukaryotic cells are typically much larger than those of prokaryotes. Internal membrane[edit] Detail of the endomembrane system and its components A 3D rendering of an animal cell cut in half. The nucleus is surrounded by a double membrane (commonly referred to as a nuclear membrane or nuclear envelope), with pores that allow material to move in and out. Vesicles may be specialized for various purposes.

Mitochondrial DNA Electron microscopy reveals mitochondrial DNA in discrete foci. Bars: 200 nm. (A) Cytoplasmic section after immunogold labelling with anti-DNA; gold particles marking mtDNA are found near the mitochondrial membrane. (B) Whole mount view of cytoplasm after extraction with CSK buffer and immunogold labelling with anti-DNA; mtDNA (marked by gold particles) resists extraction. Mitochondrial DNA (mtDNA or mDNA)[2] is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert chemical energy from food into a form that cells can use, adenosine triphosphate (ATP). In humans, mitochondrial DNA can be assessed as the smallest chromosome coding for 37 genes and containing approximately 16,600 base pairs. Origin[edit] Nuclear and mitochondrial DNA are thought to be of separate evolutionary origin, with the mtDNA being derived from the circular genomes of the bacteria that were engulfed by the early ancestors of today's eukaryotic cells. Male inheritance[edit]

Eukaryote Eukaryotes can reproduce both asexually through mitosis and sexually through meiosis and gamete fusion. In mitosis, one cell divides to produce two genetically identical cells. In meiosis, DNA replication is followed by two rounds of cell division to produce four daughter cells each with half the number of chromosomes as the original parent cell (haploid cells). These act as sex cells (gametes – each gamete has just one complement of chromosomes, each a unique mix of the corresponding pair of parental chromosomes) resulting from genetic recombination during meiosis. Cell features[edit] Eukaryotic cells are typically much larger than those of prokaryotes. Internal membrane[edit] Detail of the endomembrane system and its components A 3D rendering of an animal cell cut in half. The nucleus is surrounded by a double membrane (commonly referred to as a nuclear membrane or nuclear envelope), with pores that allow material to move in and out. Vesicles may be specialized for various purposes.

Micrograph 40x micrograph of a canine rectum cross section. A photomicrograph of a thin section of a limestone with ooids. The largest is approximately 1.2 mm in diameter. The red object in the lower left is a scale bar indicating relative size. Approximately 10x micrograph of a doubled die on a coin, where the date was struck twice. A micrograph, or photomicrograph, is a photograph or digital image taken through a microscope or similar device to show a magnified image of an item. Micrographs are widely used in all fields of microscopy. Types[edit] Photomicrograph[edit] A light micrograph or photomicrograph is a micrograph prepared using an optical microscope, a process referred to as photomicroscopy. Roman Vishniac was a pioneer in the field of photomicroscopy, specializing in the photography of living creatures in full motion. Electron micrograph[edit] An electron micrograph is a micrograph prepared using an electron microscope. Digital micrograph[edit] Magnification and micron bars[edit] Gallery[edit]

Force (Star Wars) Lucas has attributed the origins of "The Force" to a 1963 abstract film by Arthur Lipsett, which sampled from many sources. One of the audio sources Lipsett sampled for 21-87 was a conversation between artificial intelligence pioneer Warren S. McCulloch and Roman Kroitor, a cinematographer who went on to develop IMAX. In the face of McCulloch's arguments that living beings are nothing but highly complex machines, Kroitor insists that there is something more: "Many people feel that in the contemplation of nature and in communication with other living things, they become aware of some kind of force, or something, behind this apparent mask which we see in front of us, and they call it God." The Force is referenced several times throughout the Star Wars saga. In The Empire Strikes Back, Emperor Palpatine states "There is a great disturbance in the Force," in reference to Luke Skywalker. The term "Force power" originated in the Star Wars Roleplaying Game, by West End Games.

Prokaryote Cell structure of a bacterium , one of the two domains of prokaryotic life. The division to prokaryotes and eukaryotes reflects two distinct levels of cellular organization rather than biological classification of species. Prokaryotes include two major classification domains: the bacteria and the archaea . [ edit ] Relationship to eukaryotes The division to prokaryotes and eukaryotes is usually considered the most important distinction among organisms. The genome in a prokaryote is held within a DNA / protein complex in the cytosol called the nucleoid , which lacks a nuclear envelope . [ 5 ] The complex contains a single, cyclic, double-stranded molecule of stable chromosomal DNA, in contrast to the multiple linear, compact, highly organized chromosomes found in eukaryotic cells. Prokaryotes lack distinct mitochondria and chloroplasts . [ edit ] Sociality While prokaryotes are still commonly imagined to be strictly unicellular, most are capable of forming stable aggregate communities.

Golgi apparatus Micrograph of Golgi apparatus, visible as a stack of semicircular black rings near the bottom. Numerous circular vesicles can be seen in proximity to the organelle. Part of the cellular endomembrane system, the Golgi apparatus packages proteins inside the cell before they are sent to their destination; it is particularly important in the processing of proteins for secretion. Discovery Owing to its large size, the Golgi apparatus was one of the first organelles to be discovered and observed in detail. Structure Diagram of the Golgi apparatus 3D Rendering of Golgi Apparatus Found within the cytoplasm of both plant and animal cells, the Golgi is composed of stacks of membrane-bound structures known as cisternae (singular: cisterna). The cisternae stack has four functional regions: the cis-Golgi network, medial-Golgi, endo-Golgi, and trans-Golgi network. Function Cells synthesize a large number of different macromolecules. Vesicular transport Transport mechanism Fate during mitosis References

Eumetazoa Eumetazoa (Greek: εὖ [eu], well + μετά [metá], after + ζῷον [zóon], animal) is a clade comprising all major animal groups except sponges, placozoa, and several other obscure or extinct life forms, such as Dickinsonia. Characteristics of eumetazoans include true tissues organized into germ layers, and an embryo that goes through a gastrula stage. The clade is usually held to contain at least Ctenophora, Cnidaria, and Bilateria. Whether mesozoans and placozoans belong is in dispute. Some phylogenists have speculated the sponges and eumetazoans evolved separately from single-celled organisms, which would mean that the animal kingdom does not form a clade (a complete grouping of organisms descended from a common ancestor). Eumetazoans are a major group of animals in the Five Kingdoms classification of Lynn Margulis and K. Taxonomy[edit] However, many skeptics emphasize the pitfalls and inconsistencies associated with the new data. Evolutionary origins[edit] References[edit] Bilateria.

Microscope A microscope (from the Ancient Greek: μικρός, mikrós, "small" and σκοπεῖν, skopeîn, "to look" or "see") is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy. Microscopic means invisible to the eye unless aided by a microscope. There are many types of microscopes, the most common and first to be invented is the optical microscope which uses light to image the sample. History[edit] The first microscope to be developed was the optical microscope, although the original inventor is not easy to identify. Rise of modern light microscopy[edit] The first detailed account of the interior construction of living tissue based on the use of a microscope did not appear until 1644, in Giambattista Odierna's L'occhio della mosca, or The Fly's Eye.[4] It was not until the 1660s and 1670s that the microscope was used extensively for research in Italy, The Netherlands and England. Types[edit]

Force (vertu) Un article de Wikipédia, l'encyclopédie libre. Pour les articles homonymes, voir force. Sur les autres projets Wikimedia : Force (vertu), sur Wikimedia Commons Portail de la philosophie Courage Bacteria Bacteria ( Most bacteria have not been characterised, and only about half of the bacterial phyla have species that can be grown in the laboratory.[10] The study of bacteria is known as bacteriology, a branch of microbiology. Etymology Origin and early evolution Morphology Many bacterial species exist simply as single cells, others associate in characteristic patterns: Neisseria form diploids (pairs), Streptococcus form chains, and Staphylococcus group together in "bunch of grapes" clusters. Even more complex morphological changes are sometimes possible. Cellular structure Structure and contents of a typical gram-positive bacterial cell (seen by the fact that only one cell membrane is present). Intracellular structures The bacterial cell is surrounded by a cell membrane (also known as a lipid, cytoplasmic or plasma membrane). Many important biochemical reactions, such as energy generation, use concentration gradients across membranes. Extracellular structures Endospores Growth and reproduction

Cell biology Understanding cells in terms of their molecular components. Knowing the components of cells and how cells work is fundamental to all biological sciences. Appreciating the similarities and differences between cell types is particularly important to the fields of cell and molecular biology as well as to biomedical fields such as cancer research and developmental biology. These fundamental similarities and differences provide a unifying theme, sometimes allowing the principles learned from studying one cell type to be extrapolated and generalized to other cell types. Therefore, research in cell biology is closely related to genetics, biochemistry, molecular biology, immunology, and developmental biology. Processes[edit] Movement of proteins[edit] Endothelial cells under the microscope. Each type of protein is usually sent to a particular part of the cell. Other cellular processes[edit] Internal cellular structures[edit] Techniques used to study cells[edit] Notable cell biologists[edit]

GMO Human Embryos Have Already Been Created A meeting at the FDA on experiments to create GMO humans has brought disturbing information to light. Action Alert! Today, the US Food and Drug Administration held day one of a public meeting outlining the creation of genetically modified humans. These experiments won’t take place in the distant future. Specifically, the FDA is discussing the genetic manipulation of human eggs and embryos in order to prevent inherited mitochondrial disease and treat infertility. While the FDA has stated that the agency “recognizes” that there are “ethical and social policy issues” to be considered—and despite the fact that forty-four countries have already banned this kind of genetic manipulation—the FDA won’t bother to discuss if human clinical trials should take place (that’s considered to be “outside the scope” of the meeting). Some mutations in mtDNA can trigger mitochondrial disease, which can then be passed from mother to child (but not father to child). Sex selection. Action Alert!

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