1.
Chemical reaction
–
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Nuclear chemistry is a sub-discipline of chemistry that involves the reactions of unstable. The substance initially involved in a reaction are called reactants or reagents. Chemical reactions are characterized by a chemical change, and they yield one or more products. Reactions often consist of a sequence of individual sub-steps, the elementary reactions. Chemical reactions are described with chemical equations, which present the starting materials, end products. Chemical reactions happen at a characteristic reaction rate at a given temperature, typically, reaction rates increase with increasing temperature because there is more thermal energy available to reach the activation energy necessary for breaking bonds between atoms. Reactions may proceed in the forward or reverse direction until they go to completion or reach equilibrium, Reactions that proceed in the forward direction to approach equilibrium are often described as spontaneous, requiring no input of free energy to go forward. Non-spontaneous reactions require input of energy to go forward. Different chemical reactions are used in combinations during chemical synthesis in order to obtain a desired product, in biochemistry, a consecutive series of chemical reactions form metabolic pathways. These reactions are catalyzed by protein enzymes. Chemical reactions such as combustion in fire, fermentation and the reduction of ores to metals were known since antiquity, in the Middle Ages, chemical transformations were studied by Alchemists. They attempted, in particular, to lead into gold, for which purpose they used reactions of lead. The process involved heating of sulfate and nitrate minerals such as sulfate, alum. In the 17th century, Johann Rudolph Glauber produced hydrochloric acid and sodium sulfate by reacting sulfuric acid, further optimization of sulfuric acid technology resulted in the contact process in the 1880s, and the Haber process was developed in 1909–1910 for ammonia synthesis. From the 16th century, researchers including Jan Baptist van Helmont, Robert Boyle, the phlogiston theory was proposed in 1667 by Johann Joachim Becher. It postulated the existence of an element called phlogiston, which was contained within combustible bodies. This proved to be false in 1785 by Antoine Lavoisier who found the explanation of the combustion as reaction with oxygen from the air
2.
Herbivore
–
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthparts adapted to rasping or grinding, horses and other herbivores have wide flat teeth that are adapted to grinding grass, tree bark, and other tough plant material. A large percentage of herbivores have mutualistic gut flora that help them digest plant matter and this gut flora is made up of cellulose-digesting protozoans or bacteria living in the herbivores intestines. Herbivore is the form of a modern Latin coinage, herbivora. Richard Owen employed the term in an 1854 work on fossil teeth. Herbivora is derived from the Latin herba meaning a small plant or herb, Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms feed on autotrophs in general are known as primary consumers. Herbivory usually refers to eating plants, fungi, bacteria and protists that feed on living plants are usually termed plant pathogens. Flowering plants that obtain nutrition from other living plants are usually termed parasitic plants, there is however no single exclusive and definitive ecological classification of consumption patterns, each textbook has its own variations on the theme. Insects fed on the spores of early Devonian plants, and the Rhynie chert also provides evidence that organisms fed on plants using a pierce, during the next 75 million years, plants evolved a range of more complex organs, such as roots and seeds. There is no evidence of any organism being fed upon until the middle-late Mississippian,330.9 million years ago, further than their arthropod status, the identity of these early herbivores is uncertain. Hole feeding and skeletonisation are recorded in the early Permian, with surface fluid feeding evolving by the end of that period, Herbivory among four-limbed terrestrial vertebrates, the tetrapods developed in the Late Carboniferous. Early tetrapods were large amphibious piscivores, while amphibians continued to feed on fish and insects, some reptiles began exploring two new food types, tetrapods and plants. The entire dinosaur order ornithischia was composed with herbivores dinosaurs, carnivory was a natural transition from insectivory for medium and large tetrapods, requiring minimal adaptation. In contrast, a set of adaptations was necessary for feeding on highly fibrous plant materials. Arthropods evolved herbivory in four phases, changing their approach to it in response to changing plant communities, tetrapod herbivores made their first appearance in the fossil record of their jaws near the Permio-Carboniferous boundary, approximately 300 million years ago. The earliest evidence of their herbivory has been attributed to dental occlusion, the evolution of dental occlusion led to a drastic increase in plant food processing and provides evidence about feeding strategies based on tooth wear patterns. Examination of phylogenetic frameworks of tooth and jaw morphologes has revealed that dental occlusion developed independently in several lineages tetrapod herbivores and this suggests that evolution and spread occurred simultaneously within various lineages
3.
Plant
–
Plants are mainly multicellular, predominantly photosynthetic eukaryotes of the kingdom Plantae. The term is generally limited to the green plants, which form an unranked clade Viridiplantae. This includes the plants, conifers and other gymnosperms, ferns, clubmosses, hornworts, liverworts, mosses and the green algae. Green plants have cell walls containing cellulose and obtain most of their energy from sunlight via photosynthesis by primary chloroplasts and their chloroplasts contain chlorophylls a and b, which gives them their green color. Some plants are parasitic and have lost the ability to produce amounts of chlorophyll or to photosynthesize. Plants are characterized by sexual reproduction and alternation of generations, although reproduction is also common. There are about 300–315 thousand species of plants, of which the great majority, green plants provide most of the worlds molecular oxygen and are the basis of most of Earths ecologies, especially on land. Plants that produce grains, fruits and vegetables form humankinds basic foodstuffs, Plants play many roles in culture. They are used as ornaments and, until recently and in variety, they have served as the source of most medicines. The scientific study of plants is known as botany, a branch of biology, Plants are one of the two groups into which all living things were traditionally divided, the other is animals. The division goes back at least as far as Aristotle, who distinguished between plants, which generally do not move, and animals, which often are mobile to catch their food. Much later, when Linnaeus created the basis of the system of scientific classification. Since then, it has become clear that the plant kingdom as originally defined included several unrelated groups, however, these organisms are still often considered plants, particularly in popular contexts. When the name Plantae or plant is applied to a group of organisms or taxon. The evolutionary history of plants is not yet settled. Those which have been called plants are in bold, the way in which the groups of green algae are combined and named varies considerably between authors. Algae comprise several different groups of organisms which produce energy through photosynthesis, most conspicuous among the algae are the seaweeds, multicellular algae that may roughly resemble land plants, but are classified among the brown, red and green algae. Each of these groups also includes various microscopic and single-celled organisms
4.
Cassava
–
Manihot esculenta is a woody shrub native to South America of the spurge family, Euphorbiaceae. It is extensively cultivated as a crop in tropical and subtropical regions for its edible starchy tuberous root. Though it is often called yuca in Spanish and in the United States, it differs from the yucca, Cassava, when dried to a powdery extract, is called tapioca, its fermented, flaky version is named garri. Cassava is the third-largest source of carbohydrates in the tropics, after rice. Cassava is a staple food in the developing world, providing a basic diet for over half a billion people. It is one of the most drought-tolerant crops, capable of growing on marginal soils, Nigeria is the worlds largest producer of cassava, while Thailand is the largest exporter of dried cassava. Cassava is classified as sweet or bitter. Like other roots and tubers, both bitter and sweet varieties of cassava contain antinutritional factors and toxins, with the bitter varieties containing much larger amounts, the more toxic varieties of cassava are a fall-back resource in times of famine or food insecurity in some places. Farmers often prefer the bitter varieties because they deter pests, animals, the cassava root is long and tapered, with a firm, homogeneous flesh encased in a detachable rind, about 1 mm thick, rough and brown on the outside. Commercial cultivars can be 5 to 10 cm in diameter at the top, a woody vascular bundle runs along the roots axis. The flesh can be chalk-white or yellowish, Cassava roots are very rich in starch and contain small amounts of calcium, phosphorus, and vitamin C. However, they are poor in protein and other nutrients, in contrast, cassava leaves are a good source of protein, but deficient in the amino acid methionine and possibly tryptophan. Forms of the domesticated species can also be found growing in the wild in the south of Brazil. By 4,600 BC, manioc pollen appears in the Gulf of Mexico lowlands, the oldest direct evidence of cassava cultivation comes from a 1, 400-year-old Maya site, Joya de Cerén, in El Salvador. With its high potential, it had become a staple food of the native populations of northern South America, southern Mesoamerica. Cassava was a food of pre-Columbian peoples in the Americas and is often portrayed in indigenous art. The Moche people often depicted yuca in their ceramics, spaniards in their early occupation of Caribbean islands did not want to eat cassava or maize, which they considered insubstantial, dangerous, and not nutritious. They much preferred foods from Spain, specifically wheat bread, olive oil, red wine, and meat, for these Christians in the New World, cassava was not suitable for communion since it could not undergo transubstantiation and become the body of Christ
5.
Hevea brasiliensis
–
Hevea brasiliensis, the Pará rubber tree, sharinga tree, seringueira, or, most commonly, the rubber tree or rubber plant, is a tree belonging to the family Euphorbiaceae. It is the most economically important member of the genus Hevea because the milky latex extracted from the tree is the source of natural rubber. H. brasiliensis is a deciduous tree growing to a height of up to 40 m in the wild. The trunk is cylindrical and may have a swollen, bottle-shaped base, the bark is some shade of brown, and the inner bark oozes latex when damaged. The leaves have three leaflets and are spirally arranged, the inflorescence include separate male and female flowers. The flowers are pungent, creamy-yellow and have no petals, the fruit is a capsule that contains three large seeds, it opens explosively when ripe. In the wild, the tree can reach a height of up to 100 feet, the white or yellow latex occurs in latex vessels in the bark, mostly outside the phloem. These vessels spiral up the tree in a helix which forms an angle of about 30 degrees with the horizontal. The tree requires a tropical or subtropical climate with a minimum of about 1,200 mm per year of rainfall, if frost does occur, the results can be disastrous for production. One frost can cause the rubber from a plantation to become brittle. Harvesters make incisions across the vessels, just deep enough to tap the vessels without harming the trees growth. This process is known as rubber tapping, latex production is highly variable from tree to tree and across clone types. As latex production declines with age, rubber trees are generally felled when they reach the age of 25 to 30 years, the earlier practice was to burn the trees, but in recent decades, the wood has been harvested for furniture making. The Pará rubber tree initially grew only in the Amazon rainforest, increasing demand and the discovery of the vulcanization procedure in 1839 led to the rubber boom in that region, enriching the cities of Belém and Manaus. The name of the tree derives from Pará, the second-largest Brazilian state and these trees were used to obtain rubber by the natives who inhabited its geographical distribution. The Olmec people of Mesoamerica extracted and produced similar forms of primitive rubber from analogous latex-producing trees such as Castilla elastica as early as 3,600 years ago, the rubber was used, among other things, to make the balls used in the Mesoamerican ballgame. Early attempts were made in 1873 to grow H. brasilensis outside Brazil, after some effort,12 seedlings were germinated at the Royal Botanic Gardens, Kew. These were sent to India for cultivation, but died, a second attempt was then made, some 70,000 seeds being smuggled to Kew in 1875, by Henry Wickham, in the service of the British Empire
6.
Arabidopsis thaliana
–
Arabidopsis thaliana is a small flowering plant native to Eurasia. A. thaliana is considered a weed, it is found by roadsides, a winter annual with a relatively short life cycle, A. thaliana is a popular model organism in plant biology and genetics. For a complex multicellular eukaryote, A. thaliana has a small genome of approximately 135 megabase pairs. It was the first plant to have its genome sequenced, and is a tool for understanding the molecular biology of many plant traits, including flower development. Arabidopsis thaliana is a plant, usually growing to 20–25 cm tall. The leaves form a rosette at the base of the plant, leaves are covered with small, unicellular hairs. The flowers are 3 mm in diameter, arranged in a corymb, the fruit is a siliqua 5–20 mm long, containing 20–30 seeds. Roots are simple in structure, with a primary root that grows vertically downward. These roots form interactions with rhizosphere bacteria such as Bacillus megaterium, a. thaliana can complete its entire lifecycle in six weeks. The central stem produces flowers grows after about three weeks, and the flowers naturally self-pollinate. In the lab, A. thaliana may be grown in Petri plates, pots, or hydroponics, the plant was first described in 1577 in the Harz Mountains by Johannes Thal, a physician from Nordhausen, Thüringen, Germany, who called it Pilosella siliquosa. In 1753, Carl Linnaeus renamed the plant Arabis thaliana in honor of Thal, in 1842, the German botanist Gustav Heynhold erected the new genus Arabidopsis and placed the plant in that genus. The genus name, Arabidopsis, comes from Greek, meaning resembling Arabis, thousands of natural inbred accessions of A. thaliana have been collected from throughout its natural and introduced range. These accessions exhibit considerable genetic and phenotypic variation which can be used to study the adaptation of species to different environments. A. thaliana is native to Europe, Asia, and northwestern Africa and it also appears to be native in tropical afroalpine ecosystems. It has been introduced and naturalized worldwide, a. thaliana readily grows and often pioneers rocky, sandy and calcareous soils. It is generally considered a weed, due to its distribution in agricultural fields, roadside, railway lines, waste ground. Like most Brassicaceae species, A. thaliana is edible by humans as a salad or cooked, the first mutant in A. thaliana was documented in 1873 by Alexander Braun, describing a double flower phenotype
7.
Almond
–
The almond is a species of tree native to the Middle East, the Indian subcontinent and North Africa. Almond is also the name of the edible and widely cultivated seed of this tree, within the genus Prunus, it is classified with the peach in the subgenus Amygdalus, distinguished from the other subgenera by corrugations on the shell surrounding the seed. The fruit of the almond is a drupe, consisting of a hull and a hard shell with the seed. Shelling almonds refers to removing the shell to reveal the seed, almonds are sold shelled or unshelled. Blanched almonds are shelled almonds that have been treated with hot water to soften the seedcoat, the almond is a deciduous tree, growing 4–10 m in height, with a trunk of up to 30 cm in diameter. The young twigs are green at first, becoming purplish where exposed to sunlight, the leaves are 3–5 inches long, with a serrated margin and a 2.5 cm petiole. The flowers are white to pink, 3–5 cm diameter with five petals, produced singly or in pairs. Almond grows best in Mediterranean climates with warm, dry summers and mild, the optimal temperature for their growth is between 15 and 30 °C and the tree buds have a chilling requirement of 300 to 600 hours below 7.2 °C to break dormancy. Almonds begin bearing an economic crop in the year after planting. Trees reach full bearing five to six years after planting, the fruit matures in the autumn, 7–8 months after flowering. The almond fruit measures 3. 5–6 cm long, in botanical terms, it is not a nut but a drupe. The outer covering or exocarp, fleshy in other members of Prunus such as the plum and cherry, is instead a thick, leathery, grey-green coat, inside the hull is a reticulated, hard, woody shell called the endocarp. Inside the shell is the seed, commonly called a nut. Generally, one seed is present, but occasionally two occur, the almond is native to the Mediterranean climate region of the Middle East, eastward as far as the Yamuna River in India. The wild form of domesticated almond grows in parts of the Levant, the fruit of the wild forms contains the glycoside amygdalin, which becomes transformed into deadly prussic acid after crushing, chewing, or any other injury to the seed. Selection of the type from the many bitter types in the wild marked the beginning of almond domestication. It is unclear as to which wild ancestor of the created the domesticated species. Zohary and Hopf believe that almonds were one of the earliest domesticated fruit trees due to the ability of the grower to raise attractive almonds from seed
8.
Catalysis
–
Catalysis is the increase in the rate of a chemical reaction due to the participation of an additional substance called a catalyst. In most cases, reactions occur faster with a catalyst because they require less activation energy, furthermore, since they are not consumed in the catalyzed reaction, catalysts can continue to act repeatedly. Often only tiny amounts are required in principle, in the presence of a catalyst, less free energy is required to reach the transition state, but the total free energy from reactants to products does not change. A catalyst may participate in multiple chemical transformations, the effect of a catalyst may vary due to the presence of other substances known as inhibitors or poisons or promoters. Catalyzed reactions have an activation energy than the corresponding uncatalyzed reaction, resulting in a higher reaction rate at the same temperature. However, the mechanics of catalysis is complex. Usually, the catalyst participates in this slowest step, and rates are limited by amount of catalyst, in heterogeneous catalysis, the diffusion of reagents to the surface and diffusion of products from the surface can be rate determining. A nanomaterial-based catalyst is an example of a heterogeneous catalyst, analogous events associated with substrate binding and product dissociation apply to homogeneous catalysts. Although catalysts are not consumed by the reaction itself, they may be inhibited, deactivated, in heterogeneous catalysis, typical secondary processes include coking where the catalyst becomes covered by polymeric side products. Additionally, heterogeneous catalysts can dissolve into the solution in a system or sublimate in a solid–gas system. The production of most industrially important chemicals involves catalysis, similarly, most biochemically significant processes are catalysed. Research into catalysis is a field in applied science and involves many areas of chemistry, notably organometallic chemistry. Catalysis is relevant to aspects of environmental science, e. g. the catalytic converter in automobiles. Many transition metals and transition metal complexes are used in catalysis as well, Catalysts called enzymes are important in biology. A catalyst works by providing a reaction pathway to the reaction product. The rate of the reaction is increased as this route has a lower activation energy than the reaction route not mediated by the catalyst. The disproportionation of hydrogen peroxide creates water and oxygen, as shown below,2 H2O2 →2 H2O + O2 This reaction is preferable in the sense that the reaction products are more stable than the starting material, though the uncatalysed reaction is slow. In fact, the decomposition of hydrogen peroxide is so slow that hydrogen peroxide solutions are commercially available and this reaction is strongly affected by catalysts such as manganese dioxide, or the enzyme peroxidase in organisms
9.
Amino acid
–
Amino acids are organic compounds containing amine and carboxyl functional groups, along with a side chain specific to each amino acid. The key elements of an acid are carbon, hydrogen, oxygen. About 500 amino acids are known and can be classified in many ways, in the form of proteins, amino acids comprise the second-largest component of human muscles, cells and other tissues. Outside proteins, amino acids perform critical roles in such as neurotransmitter transport. In biochemistry, amino acids having both the amine and the acid groups attached to the first carbon atom have particular importance. They are known as 2-, alpha-, or α-amino acids and they include the 22 proteinogenic amino acids, which combine into peptide chains to form the building-blocks of a vast array of proteins. These are all L-stereoisomers, although a few D-amino acids occur in bacterial envelopes, as a neuromodulator, twenty of the proteinogenic amino acids are encoded directly by triplet codons in the genetic code and are known as standard amino acids. The other two are selenocysteine, and pyrrolysine, pyrrolysine and selenocysteine are encoded via variant codons, for example, selenocysteine is encoded by stop codon and SECIS element. N-formylmethionine is generally considered as a form of methionine rather than as a separate proteinogenic amino acid, codon–tRNA combinations not found in nature can also be used to expand the genetic code and create novel proteins known as alloproteins incorporating non-proteinogenic amino acids. Many important proteinogenic and non-proteinogenic amino acids also play critical roles within the body. Nine proteinogenic amino acids are called essential for humans because they cannot be created from other compounds by the human body, others may be conditionally essential for certain ages or medical conditions. Essential amino acids may also differ between species, because of their biological significance, amino acids are important in nutrition and are commonly used in nutritional supplements, fertilizers, and food technology. Industrial uses include the production of drugs, biodegradable plastics, the first few amino acids were discovered in the early 19th century. In 1806, French chemists Louis-Nicolas Vauquelin and Pierre Jean Robiquet isolated a compound in asparagus that was subsequently named asparagine, cystine was discovered in 1810, although its monomer, cysteine, remained undiscovered until 1884. Glycine and leucine were discovered in 1820, usage of the term amino acid in the English language is from 1898. Proteins were found to yield amino acids after enzymatic digestion or acid hydrolysis, in the structure shown at the top of the page, R represents a side chain specific to each amino acid. The carbon atom next to the group is called the α–carbon. Amino acids containing an amino group bonded directly to the alpha carbon are referred to as amino acids
10.
Enzyme
–
Enzymes /ˈɛnzaɪmz/ are macromolecular biological catalysts. Enzymes accelerate, or catalyze, chemical reactions, the molecules at the beginning of the process upon which enzymes may act are called substrates and the enzyme converts these into different molecules, called products. Almost all metabolic processes in the cell need enzymes in order to occur at rates fast enough to sustain life, the set of enzymes made in a cell determines which metabolic pathways occur in that cell. The study of enzymes is called enzymology, enzymes are known to catalyze more than 5,000 biochemical reaction types. Most enzymes are proteins, although a few are catalytic RNA molecules, enzymes specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the rate of a reaction by lowering its activation energy, some enzymes can make their conversion of substrate to product occur many millions of times faster. An extreme example is orotidine 5-phosphate decarboxylase, which allows a reaction that would take millions of years to occur in milliseconds. Chemically, enzymes are like any catalyst and are not consumed in chemical reactions, enzymes differ from most other catalysts by being much more specific. Enzyme activity can be affected by other molecules, inhibitors are molecules that decrease enzyme activity, many drugs and poisons are enzyme inhibitors. An enzymes activity decreases markedly outside its optimal temperature and pH, some enzymes are used commercially, for example, in the synthesis of antibiotics. French chemist Anselme Payen was the first to discover an enzyme, diastase and he wrote that alcoholic fermentation is an act correlated with the life and organization of the yeast cells, not with the death or putrefaction of the cells. In 1877, German physiologist Wilhelm Kühne first used the term enzyme, the word enzyme was used later to refer to nonliving substances such as pepsin, and the word ferment was used to refer to chemical activity produced by living organisms. Eduard Buchner submitted his first paper on the study of yeast extracts in 1897, in a series of experiments at the University of Berlin, he found that sugar was fermented by yeast extracts even when there were no living yeast cells in the mixture. He named the enzyme that brought about the fermentation of sucrose zymase, in 1907, he received the Nobel Prize in Chemistry for his discovery of cell-free fermentation. Following Buchners example, enzymes are usually named according to the reaction they carry out, the biochemical identity of enzymes was still unknown in the early 1900s. Sumner showed that the enzyme urease was a protein and crystallized it. These three scientists were awarded the 1946 Nobel Prize in Chemistry, the discovery that enzymes could be crystallized eventually allowed their structures to be solved by x-ray crystallography. This high-resolution structure of lysozyme marked the beginning of the field of structural biology, an enzymes name is often derived from its substrate or the chemical reaction it catalyzes, with the word ending in -ase
. PMID 16667728.
