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Convergent Evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is Cladogram#Homoplasies, homoplasy. The recurrent evolution of flight is a classic example, as flying pterygota, insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are ''analogous'', whereas ''homology (biology), homologous'' structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence is divergent evolution, where related species evolve different trai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Succulent Plant
In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word ''succulent'' comes from the Latin word ''sucus'', meaning "juice" or "sap". Succulents may store water in various structures, such as leaf, leaves and Plant stem, stems. The water content of some succulent organs can get up to 90–95%, such as ''Glottiphyllum semicyllindricum'' and ''Mesembryanthemum barkleyii''. Some definitions also include roots, thus geophytes that survive unfavorable periods by dying back to underground storage organs (caudex) may be regarded as succulents. The habitats of these water-preserving plants are often in areas with high temperatures and low rainfall, such as deserts, but succulents may be found even in Alpine climate, alpine ecosystems growing in rocky or sandy soil. Succulents are characterized by their ability to thrive on limited water sources, such as mist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant
Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with cyanobacteria to produce sugars from carbon dioxide and water, using the green pigment chlorophyll. Exceptions are parasitic plants that have lost the genes for chlorophyll and photosynthesis, and obtain their energy from other plants or fungi. Most plants are multicellular organism, multicellular, except for some green algae. Historically, as in Aristotle's biology, the plant kingdom encompassed all living things that were not animals, and included algae and fungi. Definitions have narrowed since then; current definitions exclude fungi and some of the algae. By the definition used in this article, plants form the clade Viridiplantae (green plants), which consists of the green algae and the embryophytes or land plants (hornworts, liverworts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wonderful Life (book)
''Wonderful Life: The Burgess Shale and the Nature of History'' is a 1989 book on the evolution of Cambrian fauna by Harvard paleontologist Stephen Jay Gould. The volume made ''The New York Times'' Best Seller list, was the 1991 winner of the Royal Society's Rhone-Poulenc Prize and the American Historical Association's Forkosch Award, and was a 1991 finalist for the Pulitzer Prize. Pulitzer juror Joyce Carol Oates later revealed the non-fiction jury had unanimously recommended the book for the prize, but the selection was rejected by the Pulitzer board. Gould described his later book ''Full House'' (1996) as a companion volume to ''Wonderful Life''. Summary Gould's thesis in ''Wonderful Life'' was that contingency plays a major role in the evolutionary history of life. He based his argument on the extraordinarily well preserved fossils of the Burgess Shale, a rich fossil-bearing deposit in Canada's Rocky Mountains, dating 505 million years ago. Gould argues that during th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme Superfamilies
A protein superfamily is the largest grouping (clade) of proteins for which common ancestry can be inferred (see homology). Usually this common ancestry is inferred from structural alignment and mechanistic similarity, even if no sequence similarity is evident. Sequence homology can then be deduced even if not apparent (due to low sequence similarity). Superfamilies typically contain several protein families which show sequence similarity within each family. The term ''protein clan'' is commonly used for protease and glycosyl hydrolases superfamilies based on the MEROPS and CAZy classification systems. Identification Superfamilies of proteins are identified using a number of methods. Closely related members can be identified by different methods to those needed to group the most evolutionarily divergent members. Sequence similarity Historically, the similarity of different amino acid sequences has been the most common method of inferring homology. Sequence similarity is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalytic Triad
A catalytic triad is a set of three coordinated amino acid residues that can be found in the active site of some enzymes. Catalytic triads are most commonly found in hydrolase and transferase enzymes (e.g. proteases, amidases, esterases, aminoacylase, acylases, lipases and β-lactamases). An acid-base (chemistry), base-nucleophile triad is a common motif for generating a nucleophilic residue for covalent catalysis. The residues form a charge-relay network to polarise and activate the nucleophile, which attacks the Substrate (chemistry), substrate, forming a covalent intermediate which is then hydrolysed to release the Product (chemistry), product and regenerate free enzyme. The nucleophile is most commonly a serine or cysteine, but occasionally threonine or even selenocysteine. The Protein tertiary structure, 3D structure of the enzyme brings together the triad residues in a precise orientation, even though they may be far apart in the sequence (Protein primary structure, primary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Site
In biology and biochemistry, the active site is the region of an enzyme where substrate molecules bind and undergo a chemical reaction. The active site consists of amino acid residues that form temporary bonds with the substrate, the ''binding site'', and residues that catalyse a reaction of that substrate, the ''catalytic site''. Although the active site occupies only ~10–20% of the volume of an enzyme, it is the most important part as it directly catalyzes the chemical reaction. It usually consists of three to four amino acids, while other amino acids within the protein are required to maintain the tertiary structure of the enzymes. Each active site is evolved to be optimised to bind a particular substrate and catalyse a particular reaction, resulting in high specificity. This specificity is determined by the arrangement of amino acids within the active site and the structure of the substrates. Sometimes enzymes also need to bind with some cofactors to fulfil their functio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme Mechanism
Enzyme catalysis is the increase in the reaction rate, rate of a process by an "enzyme", a Biomolecule, biological molecule. Most enzymes are proteins, and most such processes are chemical reactions. Within the enzyme, generally catalysis occurs at a localized site, called the active site. Most enzymes are made predominantly of proteins, either a single protein chain or many such chains in a multiprotein complex, multi-subunit complex. Enzymes often also incorporate non-protein components, such as metal ions or specialized organic molecules known as Cofactor (biochemistry), cofactor (e.g. adenosine triphosphate). Many cofactors are vitamins, and their role as vitamins is directly linked to their use in the catalysis of biological process within metabolism. Catalysis of Biochemistry, biochemical reactions in the cell (biology), cell is vital since many but not all metabolically essential reactions have very low rates when uncatalysed. One driver of protein evolution is the optimiz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homology (biology)
In biology, homology is similarity in anatomical structures or genes between organisms of different taxa due to shared ancestry, ''regardless'' of current functional differences. Evolutionary biology explains homologous structures as retained heredity from a common descent, common ancestor after having been subjected to adaptation (biology), adaptive modifications for different purposes as the result of natural selection. The term was first applied to biology in a non-evolutionary context by the anatomist Richard Owen in 1843. Homology was later explained by Charles Darwin's theory of evolution in 1859, but had been observed before this from Aristotle's biology onwards, and it was explicitly analysed by Pierre Belon in 1555. A common example of homologous structures is the forelimbs of vertebrates, where the bat wing development, wings of bats and origin of avian flight, birds, the arms of primates, the front flipper (anatomy), flippers of whales, and the forelegs of quadrupedalis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard Owen
Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomy, comparative anatomist and paleontology, palaeontologist. Owen is generally considered to have been an outstanding naturalist with a remarkable gift for interpreting fossils. Owen produced a vast array of scientific work, but is probably best remembered today for coining the word ''Dinosauria'' (meaning "Terrible Reptile" or "Fearfully Great Reptile"). An outspoken critic of Charles Darwin's theory of evolution by natural selection, Owen agreed with Darwin that evolution occurred but thought it was more complex than outlined in Darwin's ''On the Origin of Species''.[''Wikipedia:Citing sources, page range too broad''] Owen's approach to evolution can be considered to have anticipated the issues that have gained greater attention with the recent emergence of evolutionary developmental biology. Owen was the first president of the Microscopical Society of London in 1839 and edited ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecological Niche
In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources and competitors (for example, by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (for example, limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey). "The type and number of variables comprising the dimensions of an environmental niche vary from one species to another [and] the relative importance of particular environmental variables for a species may vary according to the geographic and biotic contexts". See also Chapter 2: Concepts of niches, pp. 7 ''ff'' A Grinnellian niche is determined by the habitat in which a species lives and its accompanying Behavioral ecology, behavioral adaptations. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analogous & Homologous Structures
Analogy is a comparison or correspondence between two things (or two groups of things) because of a third element that they are considered to share. In logic, it is an inference or an argument from one particular to another particular, as opposed to deduction, induction, and abduction. It is also used where at least one of the premises, or the conclusion, is general rather than particular in nature. It has the general form ''A is to B as C is to D''. In a broader sense, analogical reasoning is a cognitive process of transferring some information or meaning of a particular subject (the analog, or source) onto another (the target); and also the linguistic expression corresponding to such a process. The term analogy can also refer to the relation between the source and the target themselves, which is often (though not always) a similarity, as in the biological notion of analogy. Analogy plays a significant role in human thought processes. It has been argued that analogy lies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carnivorous Plant
Carnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans, typically insects and other arthropods, and occasionally small mammals and birds. They have adapted to grow in waterlogged sunny places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic bogs. They can be found on all continents except Antarctica, as well as many Pacific islands. In 1875, Charles Darwin published '' Insectivorous Plants'', the first treatise to recognize the significance of carnivory in plants, describing years of painstaking research. True carnivory is believed to have evolved independently at least 12 times in five different orders of flowering plants, and is represented by more than a dozen genera. This classification includes at least 583 species that attract, trap, and kill prey, absorbing the resulting available nutrients. Venus flytraps (''Dionaea muscipula''), pitcher plants, and bladderworts ('' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
