1.
Biochemistry
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Biochemistry, sometimes called biological chemistry, is the study of chemical processes within and relating to living organisms. By controlling information flow through biochemical signaling and the flow of energy through metabolism. Biochemistry is closely related to biology, the study of the molecular mechanisms by which genetic information encoded in DNA is able to result in the processes of life. Depending on the definition of the terms used, molecular biology can be thought of as a branch of biochemistry, or biochemistry as a tool with which to investigate. The chemistry of the cell depends on the reactions of smaller molecules. These can be inorganic, for water and metal ions, or organic, for example the amino acids. The mechanisms by which cells harness energy from their environment via chemical reactions are known as metabolism, the findings of biochemistry are applied primarily in medicine, nutrition, and agriculture. In medicine, biochemists investigate the causes and cures of diseases, in nutrition, they study how to maintain health and study the effects of nutritional deficiencies. In agriculture, biochemists investigate soil and fertilizers, and try to discover ways to improve crop cultivation, crop storage and pest control. However, biochemistry as a scientific discipline has its beginning sometime in the 19th century, or a little earlier. Gowland Hopkins on enzymes and the nature of biochemistry. The term biochemistry itself is derived from a combination of biology, the German chemist Carl Neuberg however is often cited to have coined the word in 1903, while some credited it to Franz Hofmeister. Then, in 1828, Friedrich Wöhler published a paper on the synthesis of urea and these techniques allowed for the discovery and detailed analysis of many molecules and metabolic pathways of the cell, such as glycolysis and the Krebs cycle. Another significant historic event in biochemistry is the discovery of the gene and this part of biochemistry is often called molecular biology. In the 1950s, James D. Watson, Francis Crick, Rosalind Franklin, in 1958, George Beadle and Edward Tatum received the Nobel Prize for work in fungi showing that one gene produces one enzyme. In 1988, Colin Pitchfork was the first person convicted of murder with DNA evidence, mello received the 2006 Nobel Prize for discovering the role of RNA interference, in the silencing of gene expression. Around two dozen of the 92 naturally occurring elements are essential to various kinds of biological life. Most rare elements on Earth are not needed by life, while a few common ones are not used, most organisms share element needs, but there are a few differences between plants and animals
2.
Sugar
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Sugar is the generic name for sweet, soluble carbohydrates, many of which are used in food. There are various types of derived from different sources. Simple sugars are called monosaccharides and include glucose, fructose, the table sugar or granulated sugar most customarily used as food is sucrose, a disaccharide of glucose and fructose. Sugar is used in prepared foods and it is added to some foods, in the body, sucrose is hydrolysed into the simple sugars fructose and glucose. Other disaccharides include maltose from malted grain, and lactose from milk, longer chains of sugars are called oligosaccharides or polysaccharides. Some other chemical substances, such as glycerol may also have a sweet taste, low-calorie food substitutes for sugar, described as artificial sweeteners, include aspartame and sucralose, a chlorinated derivative of sucrose. Sugars are found in the tissues of most plants and are present in sufficient concentrations for efficient commercial extraction in sugarcane, the world production of sugar in 2011 was about 168 million tonnes. The average person consumes about 24 kilograms of sugar each year, equivalent to over 260 food calories per person, since the latter part of the twentieth century, it has been questioned whether a diet high in sugars, especially refined sugars, is good for human health. Sugar has been linked to obesity, and suspected of, or fully implicated as a cause in the occurrence of diabetes, cardiovascular disease, dementia, macular degeneration, the etymology reflects the spread of the commodity. The English word sugar ultimately originates from the Sanskrit शर्करा, via Arabic سكر as granular or candied sugar, the contemporary Italian word is zucchero, whereas the Spanish and Portuguese words, azúcar and açúcar, respectively, have kept a trace of the Arabic definite article. The Old French word is zuchre and the contemporary French, sucre, the earliest Greek word attested is σάκχαρις. The English word jaggery, a brown sugar made from date palm sap or sugarcane juice, has a similar etymological origin – Portuguese jagara from the Sanskrit शर्करा. Sugar has been produced in the Indian subcontinent since ancient times and it was not plentiful or cheap in early times and honey was more often used for sweetening in most parts of the world. Originally, people chewed raw sugarcane to extract its sweetness, sugarcane was a native of tropical South Asia and Southeast Asia. Different species seem to have originated from different locations with Saccharum barberi originating in India and S. edule, one of the earliest historical references to sugarcane is in Chinese manuscripts dating back to 8th century BC that state that the use of sugarcane originated in India. Sugar was found in Europe by the 1st century AD, but only as an imported medicine and it is a kind of honey found in cane, white as gum, and it crunches between the teeth. It comes in lumps the size of a hazelnut, sugar is used only for medical purposes. Sugar remained relatively unimportant until the Indians discovered methods of turning sugarcane juice into granulated crystals that were easier to store, crystallized sugar was discovered by the time of the Imperial Guptas, around the 5th century AD
3.
Monosaccharide
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Monosaccharides, also called simple sugars, are the most basic units of carbohydrates. They are fundamental units of carbohydrates and cannot be hydrolyzed to simpler compounds. The general formula is CnH 2nOn and they are the simplest form of sugar and are usually colorless, water-soluble, and crystalline solids. Some monosaccharides have a sweet taste, examples of monosaccharides include glucose, fructose and galactose. Monosaccharides are the blocks of disaccharides and polysaccharides. Further, each carbon atom that supports a group is chiral, giving rise to a number of isomeric forms. For instance, galactose and glucose are both aldohexoses, but have different physical structures and chemical properties, with few exceptions, monosaccharides have this chemical formula, Cxy, where conventionally x ≥3. Monosaccharides can be classified by the x of carbon atoms they contain, triose tetrose, pentose, hexose, heptose. The most important monosaccharide, glucose, is a hexose, examples of heptoses include the ketoses mannoheptulose and sedoheptulose. Monosaccharides with eight or more carbons are rarely observed as they are quite unstable, in aqueous solutions monosaccharides exist as rings. Simple monosaccharides have a linear and unbranched carbon skeleton with one carbonyl functional group, therefore, the molecular structure of a simple monosaccharide can be written as HnmH, where n +1 + m = x, so that its elemental formula is CxH2xOx. By convention, the atoms are numbered from 1 to x along the backbone. If the carbonyl is at position 1, the molecule begins with a formyl group H− and is technically an aldehyde, in that case, the compound is termed an aldose. Otherwise, the molecule has a group, a carbonyl −− between two carbons, then it is formally a ketone, and is termed a ketose. Ketoses of biological interest usually have the carbonyl at position 2, the various classifications above can be combined, resulting in names such as aldohexose and ketotriose. A more general nomenclature for open-chain monosaccharides combines a Greek prefix to indicate the number of carbons with the suffixes -ose for aldoses, in the latter case, if the carbonyl is not at position 2, its position is then indicated by a numeric infix. So, for example, H4H is pentose, H3H is pentulose, two monosaccharides with equivalent molecular graphs may still be distinct stereoisomers, whose molecules differ in the three-dimensional arrangement of the bonds of certain atoms. This happens only if the molecule contains a center, specifically a carbon atom that is chiral
4.
Carbon
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Carbon is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds, three isotopes occur naturally, 12C and 13C being stable, while 14C is a radioactive isotope, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity, Carbon is the 15th most abundant element in the Earths crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. It is the second most abundant element in the body by mass after oxygen. The atoms of carbon can bond together in different ways, termed allotropes of carbon, the best known are graphite, diamond, and amorphous carbon. The physical properties of carbon vary widely with the allotropic form, for example, graphite is opaque and black while diamond is highly transparent. Graphite is soft enough to form a streak on paper, while diamond is the hardest naturally occurring material known, graphite is a good electrical conductor while diamond has a low electrical conductivity. Under normal conditions, diamond, carbon nanotubes, and graphene have the highest thermal conductivities of all known materials, all carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form. They are chemically resistant and require high temperature to react even with oxygen, the most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and transition metal carbonyl complexes. The largest sources of carbon are limestones, dolomites and carbon dioxide, but significant quantities occur in organic deposits of coal, peat, oil. For this reason, carbon has often referred to as the king of the elements. The allotropes of carbon graphite, one of the softest known substances, and diamond. It bonds readily with other small atoms including other carbon atoms, Carbon is known to form almost ten million different compounds, a large majority of all chemical compounds. Carbon also has the highest sublimation point of all elements, although thermodynamically prone to oxidation, carbon resists oxidation more effectively than elements such as iron and copper that are weaker reducing agents at room temperature. Carbon is the element, with a ground-state electron configuration of 1s22s22p2. Its first four ionisation energies,1086.5,2352.6,4620.5 and 6222.7 kJ/mol, are higher than those of the heavier group 14 elements. Carbons covalent radii are normally taken as 77.2 pm,66.7 pm and 60.3 pm, although these may vary depending on coordination number, in general, covalent radius decreases with lower coordination number and higher bond order. Carbon compounds form the basis of all life on Earth
5.
Pentose
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A pentose is a monosaccharide with five carbon atoms. Pentoses are organized into two groups, aldopentoses have an aldehyde functional group at position 1. Ketopentoses have a functional group in position 2 or 3. The aldopentoses have three chiral centers and therefore eight different stereoisomers are possible, the 2-ketopentoses have two chiral centers, and therefore four different stereoisomers are possible. The aldehyde and ketone functional groups in these carbohydrates react with neighbouring hydroxyl groups to form intramolecular hemiacetals and hemiketals. The resulting ring structure is related to furan, and is termed a furanose, the ring spontaneously opens and closes, allowing rotation to occur about the bond between the carbonyl group and the neighbouring carbon atom — yielding two distinct configurations. Ribose is a constituent of RNA, and the related deoxyribose of DNA, a polymer composed of pentose sugars is called a pentosan. The Tollens’ test for pentoses relies on reaction of the furfural with phloroglucinol to produce a compound with high molar absorptivity. Aniline acetate test, for distinguishing pentoses from other carbohydrates Pentose phosphate pathway Bials test Ribose
6.
Hexose
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In bio-organic chemistry, a hexose is a monosaccharide with six carbon atoms, having the chemical formula C6H12O6. Hexoses are classified by functional group, with aldohexoses having an aldehyde at position 1, the aldohexoses have four chiral centres for a total of 16 possible aldohexose stereoisomers. The D/L configuration is based on the orientation of the hydroxyl at position 5, the eight D-aldohexoses are, Of these D-isomers, all except D-altrose are naturally occurring. L-Altrose, however, has been isolated from strains of the bacterium Butyrivibrio fibrisolvens, a mnemonic for the aldohexoses is All Altruists Gladly Make Gum in Gallon Tanks, allose, altrose, glucose, mannose, gulose, idose, galactose, talose. At carbon 3, the first two are on the right, the two are on the left, and so on. At carbon 4, the first four are on the right, at carbon 5, all eight D-aldohexoses have the hydroxyl group on the right. This can be seen as binary counting to seven, where 0 stands for hydroxyl and 1 for hydrogen and it has been known since 1926 that 6-carbon aldose sugars form cyclic hemiacetals. The diagram below shows the forms for D-glucose and D-mannose. The numbered carbons in the forms correspond to the same numbered carbons in the hemiacetal forms. The formation of the hemiacetal causes carbon number 1, which is symmetric in the open-chain form and this means that both glucose and mannose each have two cyclic forms. In solution, both of these exist in equilibrium with the open-chain form, the open-chain form, however, does not crystallize. Hence the two cyclic forms become separable when they are crystallized, the ketohexoses have 3 chiral centres and therefore eight possible stereoisomers. Of these, only the four D-isomers are known to naturally, Only the naturally occurring hexoses are capable of being fermented by yeasts. The aldehyde and ketone functional groups in these carbohydrates react with neighbouring hydroxyl groups to form intramolecular hemiacetals and hemiketals. The resulting ring structure is related to pyran, and is termed a pyranose, the ring spontaneously opens and closes, allowing rotation to occur about the bond between the carbonyl group and the neighbouring carbon atom, yielding two distinct configurations. Hexose sugars can form dihexose sugars with a reaction to form a 1
7.
Aldehyde
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The group—without R—is the aldehyde group, also known as the formyl group. Aldehydes are common in organic chemistry, Aldehydes feature an sp2-hybridized, planar carbon center that is connected by a double bond to oxygen and a single bond to hydrogen. The C–H bond is not ordinarily acidic, because of resonance stabilization of the conjugate base, an α-hydrogen in an aldehyde is far more acidic, with a pKa near 15, compared to the acidity of a typical alkane. This acidification is attributed to the quality of the formyl center and the fact that the conjugate base. Related to, the group is somewhat polar. Aldehydes can exist in either the keto or the enol tautomer, keto-enol tautomerism is catalyzed by either acid or base. Usually the enol is the minority tautomer, but it is more reactive, the common names for aldehydes do not strictly follow official guidelines, such as those recommended by IUPAC, but these rules are useful. IUPAC prescribes the following nomenclature for aldehydes, Acyclic aliphatic aldehydes are named as derivatives of the longest carbon chain containing the aldehyde group, thus, HCHO is named as a derivative of methane, and CH3CH2CH2CHO is named as a derivative of butane. The name is formed by changing the suffix -e of the parent alkane to -al, so that HCHO is named methanal, in other cases, such as when a -CHO group is attached to a ring, the suffix -carbaldehyde may be used. Thus, C6H11CHO is known as cyclohexanecarbaldehyde, if the presence of another functional group demands the use of a suffix, the aldehyde group is named with the prefix formyl-. This prefix is preferred to methanoyl-, the word aldehyde was coined by Justus von Liebig as a contraction of the Latin alcohol dehydrogenatus. In the past, aldehydes were sometimes named after the corresponding alcohols, for example, the term formyl group is derived from the Latin word formica ant. This word can be recognized in the simplest aldehyde, formaldehyde, Aldehydes have properties that are diverse and that depend on the remainder of the molecule. Smaller aldehydes are more soluble in water, formaldehyde and acetaldehyde completely so, the volatile aldehydes have pungent odors. Aldehydes degrade in air via the process of autoxidation, the two aldehydes of greatest importance in industry, formaldehyde and acetaldehyde, have complicated behavior because of their tendency to oligomerize or polymerize. They also tend to hydrate, forming the geminal diol, the oligomers/polymers and the hydrates exist in equilibrium with the parent aldehyde. Aldehydes are readily identified by spectroscopic methods, using IR spectroscopy, they display a strong νCO band near 1700 cm−1. In their 1H NMR spectra, the formyl hydrogen center absorbs near δH =9 and this signal shows the characteristic coupling to any protons on the alpha carbon
8.
Aldose
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An aldose, like a ketose, is a monosaccharide that contains only one aldehyde group per molecule, whereas ketose contains a ketone group. The chemical formula takes the form Cnn, the simplest possible aldose is the diose glycolaldehyde, which only contains two carbon atoms. Because they have at least one carbon center, aldoses with three or more carbon atoms exhibit stereoisomerism. Aldoses containing stereogenic centers can exist in either a D- form or L- form, biological systems tend to recognize D-aldoses more than L-aldoses. Examples of aldose include glycolaldehyde, glyceraldehyde, erythrose, threose, ribose, arabinose, xylose, lyxose, allose, altrose, glucose, mannose, gulose, idose, talose, all of these examples contain one group of aldehyde. They only differ in numbers of carbons in carbon skeleton, all of these complex sugars serve an important role in biochemistry. An aldose differs from a ketose in that it has a group at the end of the carbon chain instead of in the middle. This allows ketoses and aldoses to be differentiated through Seliwanoffs test. In Seliwanoffs test, aldoses tend to react in a slow pace, with different color of production, aldoses can be differentiate from the ketoses. An aldose may isomerize to a ketose through the Lobry-de Bruyn-van Ekenstein transformation, aldose and ketose, although differ in structures, also perform in different roles. Aldoses tend to isomerise into ketoses
9.
Ketone
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In chemistry, a ketone /ˈkiːtoʊn/ is an organic compound with the structure RCR, where R and R can be a variety of carbon-containing substituents. Ketones and aldehydes are simple compounds that contain a carbonyl group and they are considered simple because they do not have reactive groups like −OH or −Cl attached directly to the carbon atom in the carbonyl group, as in carboxylic acids containing −COOH. Many ketones are known and many are of importance in industry. Examples include many sugars and the industrial solvent acetone, which is the smallest ketone, the word ketone is derived from Aketon, an old German word for acetone. According to the rules of IUPAC nomenclature, ketones are named by changing the suffix -ane of the parent alkane to -anone, the position of the carbonyl group is usually denoted by a number. For the most important ketones, however, traditional names are still generally used. The common names of ketones are obtained by writing separately the names of the two alkyl groups attached to the group, followed by ketone as a separate word. The names of the groups are written alphabetically. When the two groups are the same, the prefix di- is added before the name of alkyl group. The positions of other groups are indicated by Greek letters, the α-carbon being the adjacent to carbonyl group. If both alkyl groups in a ketone are the same then the ketone is said to be symmetrical, although used infrequently, oxo is the IUPAC nomenclature for a ketone functional group. Other prefixes, however, are also used, for some common chemicals, keto or oxo refer to the ketone functional group. The term oxo is used widely through chemistry, for example, it also refers to an oxygen atom bonded to a transition metal. The ketone carbon is often described as sp2 hybridized, a description that includes both their electronic and molecular structure, ketones are trigonal planar around the ketonic carbon, with C−C−O and C−C−C bond angles of approximately 120°. Ketones differ from aldehydes in that the group is bonded to two carbons within a carbon skeleton. In aldehydes, the carbonyl is bonded to one carbon and one hydrogen and are located at the ends of carbon chains, ketones are also distinct from other carbonyl-containing functional groups, such as carboxylic acids, esters and amides. The carbonyl group is polar because the electronegativity of the oxygen is greater than that for carbon, thus, ketones are nucleophilic at oxygen and electrophilic at carbon. Because the carbonyl group interacts with water by bonding, ketones are typically more soluble in water than the related methylene compounds
10.
Ketose
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A ketose is a monosaccharide containing one ketone group per molecule. With three carbon atoms, dihydroxyacetone is the simplest of all ketoses and is the one having no optical activity. Ketoses can isomerize into an aldose when the group is located at the end of the molecule
11.
Polysaccharide
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They range in structure from linear to highly branched. Examples include storage polysaccharides such as starch and glycogen, and structural polysaccharides such as cellulose, polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. Depending on the structure, these macromolecules can have distinct properties from their building blocks. They may be amorphous or even insoluble in water, natural saccharides are generally of simple carbohydrates called monosaccharides with general formula n where n is three or more. Examples of monosaccharides are glucose, fructose, and glyceraldehyde, polysaccharides, meanwhile, have a general formula of Cxy where x is usually a large number between 200 and 2500. When the repeating units in the backbone are six-carbon monosaccharides, as is often the case, the general formula simplifies to n. Polysaccharides are an important class of biological polymers and their function in living organisms is usually either structure- or storage-related. Starch is used as a polysaccharide in plants, being found in the form of both amylose and the branched amylopectin. In animals, the structurally similar glucose polymer is the more densely branched glycogen, glycogens properties allow it to be metabolized more quickly, which suits the active lives of moving animals. Cellulose and chitin are examples of structural polysaccharides, cellulose is used in the cell walls of plants and other organisms, and is said to be the most abundant organic molecule on Earth. It has many such as a significant role in the paper and textile industries, and is used as a feedstock for the production of rayon, cellulose acetate, celluloid. Chitin has a structure, but has nitrogen-containing side branches. It is found in arthropod exoskeletons and in the walls of some fungi. It also has multiple uses, including surgical threads, polysaccharides also include callose or laminarin, chrysolaminarin, xylan, arabinoxylan, mannan, fucoidan and galactomannan. Nutrition polysaccharides are common sources of energy, many organisms can easily break down starches into glucose, however, most organisms cannot metabolize cellulose or other polysaccharides like chitin and arabinoxylans. These carbohydrate types can be metabolized by bacteria and protists. Ruminants and termites, for example, use microorganisms to process cellulose, even though these complex carbohydrates are not very digestible, they provide important dietary elements for humans. Called dietary fiber, these carbohydrates enhance digestion among other benefits, the main action of dietary fiber is to change the nature of the contents of the gastrointestinal tract, and to change how other nutrients and chemicals are absorbed
12.
Lactose
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Lactose is a disaccharide sugar composed of galactose and glucose that is found in milk. Lactose makes up around 2–8% of milk, although the amount varies among species and individuals and it is extracted from sweet or sour whey. The name comes from lac, the Latin word for milk and it has a formula of C12H22O11 and the hydrate formula C12H22O11·H2O, making it an isomer of sucrose. The first crude isolation of lactose, by Italian physician Fabrizio Bartoletti, was published in 1633, in 1700, the Venetian pharmacist Lodovico Testi published a booklet of testimonials to the power of milk sugar to relieve, among other ailments, the symptoms of arthritis. In 1715, Testis procedure for making milk sugar was published by Antonio Vallisneri, lactose was identified as a sugar in 1780 by Carl Wilhelm Scheele. In 1812, Heinrich Vogel recognized that glucose was a product of hydrolyzing lactose, in 1856, Louis Pasteur crystallized the other component of lactose, galactose. By 1894, Emil Fischer had established the configurations of the component sugars, lactose was named by the French chemist Jean Baptiste André Dumas in 1843. Lactose is a derived from the condensation of galactose and glucose. Lactose is hydrolysed to glucose and galactose, isomerised in alkaline solution to lactulose, lactose monohydrate crystals have a characteristic tomahawk shape that can be observed with a light microscope. Several million tons are produced annually as a by-product of the dairy industry, whey is made up of 6. 5% solids of which 4. 8% is lactose that may be purified by crystallisation. Whey or milk plasma is the liquid remaining after milk is curdled and strained, lactose makes up about 2–8% of milk by weight. Industrially, lactose is produced from whey permeate – that is whey filtrated for all major proteins, the protein fraction is used in infant nutrition and sport nutrition while the permeate can be evaporated to 60–65% solids and crystallized while cooling. Lactose can also be precipitated from whey using ethanol, since it is insoluble in ethanol, lactose precipitates, in about 65% yield. Infant mammals nurse on their mothers to drink milk, which is rich in lactose, the intestinal villi secrete the enzyme called lactase to digest it. This enzyme cleaves the molecule into its two subunits, the simple sugars glucose and galactose, which can be absorbed. Since lactose occurs mostly in milk, in most mammals, the production of lactase gradually decreases with maturity due to a lack of continuing consumption. Many people with ancestry in Europe, West Asia, South Asia, the Sahel belt in West Africa, East Africa, in many of these areas, milk from mammals such as cattle, goats, and sheep is used as a large source of food. Hence, it was in these regions that genes for lifelong lactase production first evolved, the genes of adult lactose tolerance have evolved independently in various ethnic groups
13.
Milk
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Milk is a pale liquid produced by the mammary glands of mammals. It is the source of nutrition for infant mammals before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mothers antibodies to its young and it contains many other nutrients including protein and lactose. As an agricultural product, milk is extracted from non-human mammals during or soon after pregnancy, Dairy farms produced about 730 million tonnes of milk in 2011, from 260 million dairy cows. India is the worlds largest producer of milk, and is the leading exporter of skimmed milk powder, the ever increasing rise in domestic demand for dairy products and a large demand-supply gap could lead to India being a net importer of dairy products in the future. The United States, India, China and Brazil are the worlds largest exporters of milk and milk products, China and Russia were the worlds largest importers of milk and milk products until 2016 when both countries became self-sufficient, contributing to a worldwide glut of milk. Throughout the world, there are more than six billion consumers of milk and milk products, over 750 million people live in dairy farming households. The term milk comes from Old English meoluc, milc, from Proto-Germanic *meluks milk, there are two distinct types of milk consumption, a natural source of nutrition for all infant mammals and a food product for humans of all ages that is derived from other animals. In almost all mammals, milk is fed to infants through breastfeeding, the early milk from mammals is called colostrum. Colostrum contains antibodies that provide protection to the baby as well as nutrients. The makeup of the colostrum and the period of secretion varies from species to species, for humans, the World Health Organization recommends exclusive breastfeeding for six months and breastfeeding in addition to other food for at least two years. In some cultures it is common to breastfeed children for three to five years, and the period may be longer, fresh goats milk is sometimes substituted for breast milk. This introduces the risk of the child developing electrolyte imbalances, metabolic acidosis, megaloblastic anemia, in many cultures of the world, especially the West, humans continue to consume milk beyond infancy, using the milk of other animals as a food product. Initially, the ability to digest milk was limited to children as adults did not produce lactase, Milk was therefore converted to curd, cheese and other products to reduce the levels of lactose. Thousands of years ago, a chance mutation spread in human populations in Europe that enabled the production of lactase in adulthood and this allowed milk to be used as a new source of nutrition which could sustain populations when other food sources failed. Milk is processed into a variety of products such as cream, butter, yogurt, kefir, ice cream. Modern industrial processes use milk to produce casein, whey protein, lactose, condensed milk, powdered milk, whole milk, butter and cream have high levels of saturated fat. The sugar lactose is found only in milk, forsythia flowers, the enzyme needed to digest lactose, lactase, reaches its highest levels in the small intestine after birth and then begins a slow decline unless milk is consumed regularly
14.
Latin
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Latin is a classical language belonging to the Italic branch of the Indo-European languages. The Latin alphabet is derived from the Etruscan and Greek alphabets, Latin was originally spoken in Latium, in the Italian Peninsula. Through the power of the Roman Republic, it became the dominant language, Vulgar Latin developed into the Romance languages, such as Italian, Portuguese, Spanish, French, and Romanian. Latin, Italian and French have contributed many words to the English language, Latin and Ancient Greek roots are used in theology, biology, and medicine. By the late Roman Republic, Old Latin had been standardised into Classical Latin, Vulgar Latin was the colloquial form spoken during the same time and attested in inscriptions and the works of comic playwrights like Plautus and Terence. Late Latin is the language from the 3rd century. Later, Early Modern Latin and Modern Latin evolved, Latin was used as the language of international communication, scholarship, and science until well into the 18th century, when it began to be supplanted by vernaculars. Ecclesiastical Latin remains the language of the Holy See and the Roman Rite of the Catholic Church. Today, many students, scholars and members of the Catholic clergy speak Latin fluently and it is taught in primary, secondary and postsecondary educational institutions around the world. The language has been passed down through various forms, some inscriptions have been published in an internationally agreed, monumental, multivolume series, the Corpus Inscriptionum Latinarum. Authors and publishers vary, but the format is about the same, volumes detailing inscriptions with a critical apparatus stating the provenance, the reading and interpretation of these inscriptions is the subject matter of the field of epigraphy. The works of several hundred ancient authors who wrote in Latin have survived in whole or in part and they are in part the subject matter of the field of classics. The Cat in the Hat, and a book of fairy tales, additional resources include phrasebooks and resources for rendering everyday phrases and concepts into Latin, such as Meissners Latin Phrasebook. The Latin influence in English has been significant at all stages of its insular development. From the 16th to the 18th centuries, English writers cobbled together huge numbers of new words from Latin and Greek words, dubbed inkhorn terms, as if they had spilled from a pot of ink. Many of these words were used once by the author and then forgotten, many of the most common polysyllabic English words are of Latin origin through the medium of Old French. Romance words make respectively 59%, 20% and 14% of English, German and those figures can rise dramatically when only non-compound and non-derived words are included. Accordingly, Romance words make roughly 35% of the vocabulary of Dutch, Roman engineering had the same effect on scientific terminology as a whole
15.
Starch
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Starch or amylum is a polymeric carbohydrate consisting of a large number of glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants as an energy store and it is the most common carbohydrate in human diets and is contained in large amounts in staple foods such as potatoes, wheat, maize, rice, and cassava. Pure starch is a white, tasteless and odorless powder that is insoluble in water or alcohol. It consists of two types of molecules, the linear and helical amylose and the branched amylopectin, depending on the plant, starch generally contains 20 to 25% amylose and 75 to 80% amylopectin by weight. Glycogen, the store of animals, is a more branched version of amylopectin. In industry, starch is converted into sugars, for example by malting and it is processed to produce many of the sugars used in processed foods. Dissolving starch in water gives wheatpaste, which can be used as a thickening, stiffening or gluing agent. The biggest industrial non-food use of starch is as an adhesive in the papermaking process, starch can be applied to parts of some garments before ironing, to stiffen them. The word starch is from a Germanic root with the strong, stiff. Amylum for starch is from the Greek αμυλον, amylon which means not ground at a mill, the root amyl is used in biochemistry for several compounds related to starch. Starch grains from the rhizomes of Typha as flour have been identified from grinding stones in Europe dating back to 30,000 years ago, starch grains from sorghum were found on grind stones in caves in Ngalue, Mozambique dating up to 100,000 years ago. Pure extracted wheat starch paste was used in Ancient Egypt possibly to glue papyrus, the extraction of starch is first described in the Natural History of Pliny the Elder around AD 77–79. Romans used it also in cosmetic creams, to powder the hair, persians and Indians used it to make dishes similar to gothumai wheat halva. Rice starch as surface treatment of paper has been used in production in China. In addition to starchy plants consumed directly,66 million tonnes of starch were being produced per year world-wide by 2008. In the EU this was around 8.5 million tonnes, with around 40% being used for applications and 60% for food uses. Most green plants use starch as their energy store, an exception is the family Asteraceae, where starch is replaced by the fructan inulin. In photosynthesis, plants use light energy to produce glucose from carbon dioxide, the glucose is used to make cellulose fibers, the structural component of the plant, or is stored in the form of starch granules, in amyloplasts
16.
Amylose
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Amylose is a helical polymer made of α-D-glucose units, bonded to each other through α glycosidic bonds. This polysaccharide is one of the two components of starch, making up approximately 20-30% of the structure, the other component is amylopectin, which makes up 70–80% of the structure. Amylose is made up of α bound glucose molecules, the carbon atoms on glucose are numbered, starting at the aldehyde carbon, so, in amylose, the 1-carbon on one glucose molecule is linked to the 4-carbon on the next glucose molecule. The structural formula of amylose is pictured at right, the number of repeated glucose subunits is usually in the range of 300 to 3000, but can be many thousands. There are three forms of amylose chains can take. It can exist in a disordered amorphous conformation or two different helical forms and it can bind with itself in a double helix, or it can bind with another hydrophobic guest molecule such as iodine, a fatty acid, or an aromatic compound. This is known as the V form and is how amylopectin binds to amylose to form starch, within this group, there are many different variations. Each is notated with V and then a subscript indicating the number of units per turn. The most common is the V6 form, which has six glucose units a turn, v8 and possibly V7 forms exist as well. These provide a larger space for the guest molecule to bind. This linear structure can have some rotation around the phi and psi angles, because the long linear chains of amylose more readily crystallize than amylopectin, high-amylose starch is more resistant to digestion. Unlike amylopectin, amylose is not soluble in cold water and it also reduces the crystallinity of amylopectin and how easily water can infiltrate the starch. The higher the content, the less expansion potential and the lower the gel strength for the same starch concentration. This can be countered partially by increasing the granule size, fiber X-ray diffraction analysis coupled with computer-based structure refinement has found A-, B-, and C- polymorphs of amylose. Each form corresponds to either the A-, the B-, or the C- starch forms, Amylose is important in plant energy storage. It is less readily digested than amylopectin, however, because it is more linear than amylopectin, as a result, it is the preferred starch for storage in plants. It makes up about 30% of the starch in plants. The digestive enzyme α-amylase is responsible for the breakdown of the molecule into maltotriose and maltose
17.
Sucrose
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Sucrose is a common saccharide found in many plants and plant parts. Saccharose is a term for sugars in general, especially sucrose. The molecule is a combination of the monosaccharides glucose and fructose with the formula C12H22O11. Sucrose is often extracted and refined from either sugarcane or beet sugar for human consumption, modern industrial sugar refinement processes often involve bleaching and crystallization, producing a white, odorless, crystalline powder with a sweet taste of pure sucrose. This refined form of sucrose is commonly referred to as sugar or just sugar. It plays a role as an additive in food production all over the world. About 175 million metric tons of sucrose were produced worldwide in 2013, the term sucrose was first used in 1857 by English chemist William Miller from the French sucre and the generic chemical suffix for sugars -ose. The abbreviated term Suc is often used for sucrose in scientific literature, in sucrose, the components glucose and fructose are linked via an acetal bond between C1 on the glucosyl subunit and C2 on the fructosyl unit. The bond is called a glycosidic linkage, glucose exists predominantly as two isomeric pyranoses, but only one of these forms links to the fructose. Fructose itself exists as a mixture of furanoses, each of which having α and β isomers and this linkage inhibits further bonding to other saccharide units. Since it contains no anomeric hydroxyl groups, it is classified as a non-reducing sugar. Sucrose crystallizes in the space group P21 with room-temperature lattice parameters a =1.08631 nm, b =0.87044 nm, c =0.77624 nm. The purity of sucrose is measured by polarimetry, through the rotation of plane-polarized light by a solution of sugar, the specific rotation at 20 °C using yellow sodium-D light is +66. 47°. Commercial samples of sugar are assayed using this parameter, Sucrose does not deteriorate at ambient conditions. The formula for sucrose decomposition can be represented as a 2 step reaction, C12H22O11 + heat → 12C + 11H2O 12C + 12O2 → 12CO2 Sucrose does not melt at high temperatures. Instead, it decomposes—at 186 °C —to form caramel, like other carbohydrates, it combusts to carbon dioxide and water. Mixing sucrose with the potassium nitrate produces the fuel known as rocket candy that is used to propel amateur rocket motors. C12H22O11 +6 KNO3 →9 CO +3 N2 +11 H2O +3 K2CO3 This reaction is somewhat simplified though, some of the carbon does get fully oxidized to carbon dioxide, and other reactions, such as the water-gas shift reaction also take place
18.
IUPAC nomenclature of organic chemistry
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It is published in the Nomenclature of Organic Chemistry. Ideally, every possible organic compound should have a name from which a structural formula can be created. There is also an IUPAC nomenclature of inorganic chemistry, otherwise the common or trivial name may be used, often derived from the source of the compound. In addition, very long names may be less concise than structural formulae, in chemistry, a number of prefixes, suffixes and infixes are used to describe the type and position of functional groups in the compound. The steps for naming an organic compound are, Identification of the parent hydrocarbon chain and this chain must obey the following rules, in order of precedence, It should have the maximum number of substituents of the suffix functional group. By suffix, it is meant that the parent functional group should have a suffix, if more than one functional group is present, the one with highest precedence should be used. It should have the number of multiple bonds It should have the maximum number of single bonds. It should have the maximum length, Identification of the parent functional group, if any, with the highest order of precedence. Side chains are the chains that are not in the parent chain. Identification of the functional groups, if any, and naming them by their ionic prefixes. Different side-chains and functional groups will be grouped together in alphabetical order, when both side chains and secondary functional groups are present, they should be written mixed together in one group rather than in two separate groups. Locants are the numbers on the carbons to which the substituent is directly attached, has the lowest-numbered locants for multiple bonds. Has the lowest-numbered locants for prefixes, numbering of the various substituents and bonds with their locants. If there are two side-chains with the alpha carbon, the number will be written twice. If there are double bonds and triple bonds, en is written before yne. When the main group is a terminal functional group, there is no need to number it. Wherever it says with numbers, it is understood that between the word and the numbers, the prefix is used. Adding of punctuation, Commas are put between numbers Hyphens are put between a number and a letter Successive words are merged into one word Note, IUPAC uses one-word names throughout and this is why all parts are connected
19.
Alkane
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In organic chemistry, an alkane, or paraffin, is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a structure in which all the carbon-carbon bonds are single. Alkanes have the chemical formula CnH2n+2. The alkanes range in complexity from the simplest case of methane, CH4 where n =1, in an alkane, each carbon atom has 4 bonds, and each hydrogen atom is joined to one of the carbon atoms. The longest series of linked carbon atoms in a molecule is known as its skeleton or carbon backbone. The number of atoms may be thought of as the size of the alkane. One group of the alkanes are waxes, solids at standard ambient temperature and pressure. They can be viewed as molecular trees upon which can be hung the more functional groups of biological molecules. The alkanes have two main sources, petroleum and natural gas. Saturated hydrocarbons are hydrocarbons having only single covalent bonds between their carbons, according to the definition by IUPAC, the former two are alkanes, whereas the third group is called cycloalkanes. Saturated hydrocarbons can also combine any of the linear, cyclic and branching structures, the formula is CnH 2n−2k+2. Alkanes are the ones, corresponding to k =0. Alkanes with more than three carbon atoms can be arranged in different ways, forming structural isomers. The simplest isomer of an alkane is the one in which the atoms are arranged in a single chain with no branches. This isomer is called the n-isomer. However the chain of atoms may also be branched at one or more points. The number of possible isomers increases rapidly with the number of carbon atoms, for example, 3-methylhexane and its higher homologues are chiral due to their stereogenic center at carbon atom number 3. In addition to the alkane isomers, the chain of atoms may form one or more loops
20.
Alkene
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In organic chemistry, an alkene is an unsaturated hydrocarbon that contains at least one carbon–carbon double bond. The words alkene, olefin, and olefine are used often interchangeably, acyclic alkenes, with only one double bond and no other functional groups, known as mono-enes, form a homologous series of hydrocarbons with the general formula CnH2n. Alkenes have two hydrogen atoms less than the corresponding alkane, the simplest alkene, ethylene, with the International Union of Pure and Applied Chemistry name ethene, is the organic compound produced on the largest scale industrially. Aromatic compounds are drawn as cyclic alkenes, but their structure and properties are different. This double bond is stronger than a single covalent bond and also shorter, each carbon of the double bond uses its three sp2 hybrid orbitals to form sigma bonds to three atoms. The unhybridized 2p atomic orbitals, which lie perpendicular to the created by the axes of the three sp² hybrid orbitals, combine to form the pi bond. This bond lies outside the main C–C axis, with half of the bond on one side of the molecule, rotation about the carbon–carbon double bond is restricted because it incurs an energetic cost to break the alignment of the p orbitals on the two carbon atoms. As a consequence, substituted alkenes may exist as one of two isomers, called cis or trans isomers, more complex alkenes may be named with the E–Z notation for molecules with three or four different substituents. For example, of the isomers of butene, the two groups of -but-2-ene appear on the same side of the double bond, and in -but-2-ene the methyl groups appear on opposite sides. These two isomers of butene are slightly different in their chemical and physical properties, a 90° twist of the C=C bond requires less energy than the strength of a pi bond, and the bond still holds. This contradicts a common assertion that the p orbitals would be unable sustain such a bond. In truth, the misalignment of the p orbitals is less than expected because pyramidalization takes place, trans-Cyclooctene is a stable strained alkene and the orbital misalignment is only 19° with a dihedral angle of 137° and a degree of pyramidalization of 18°. The trans isomer of cycloheptene is stable only at low temperatures, as predicted by the VSEPR model of electron pair repulsion, the molecular geometry of alkenes includes bond angles about each carbon in a double bond of about 120°. The angle may vary because of steric strain introduced by nonbonded interactions between groups attached to the carbons of the double bond. For example, the C–C–C bond angle in propylene is 123. 9°, for bridged alkenes, Bredts rule states that a double bond cannot occur at the bridgehead of a bridged ring system unless the rings are large enough. The physical properties of alkenes and alkanes are similar and they are colourless, nonpolar, combustable, and almost odorless. The physical state depends on mass, like the corresponding saturated hydrocarbons, the simplest alkenes, ethene, propene. Linear alkenes of approximately five to sixteen carbons are liquids, Alkenes are relatively stable compounds, but are more reactive than alkanes, either because of the reactivity of the carbon–carbon pi-bond or the presence of allylic CH centers
21.
Hydrocarbon
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In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon, and thus are group 14 hydrides. Hydrocarbons from which one atom has been removed are functional groups. Aromatic hydrocarbons, alkanes, alkenes, cycloalkanes and alkyne-based compounds are different types of hydrocarbons, the classifications for hydrocarbons, defined by IUPAC nomenclature of organic chemistry are as follows, Saturated hydrocarbons are the simplest of the hydrocarbon species. They are composed entirely of single bonds and are saturated with hydrogen, the formula for acyclic saturated hydrocarbons is CnH2n+2. The most general form of saturated hydrocarbons is CnH2n+2, where r is the number of rings and those with exactly one ring are the cycloalkanes. Saturated hydrocarbons are the basis of petroleum fuels and are found as linear or branched species. Substitution reaction is their characteristics property, hydrocarbons with the same molecular formula but different structural formulae are called structural isomers. As given in the example of 3-methylhexane and its higher homologues, chiral saturated hydrocarbons constitute the side chains of biomolecules such as chlorophyll and tocopherol. Unsaturated hydrocarbons have one or more double or triple bonds between carbon atoms and those with double bond are called alkenes. Those with one double bond have the formula CnH2n and those containing triple bonds are called alkyne. Those with one triple bond have the formula CnH2n−2, aromatic hydrocarbons, also known as arenes, are hydrocarbons that have at least one aromatic ring. Hydrocarbons can be gases, liquids, waxes or low melting solids or polymers, in terms of shells, carbon consists of an incomplete outer shell, which comprises 4 electrons, and thus has 4 electrons available for covalent or dative bonding. Some hydrocarbons also are abundant in the solar system, lakes of liquid methane and ethane have been found on Titan, Saturns largest moon, confirmed by the Cassini-Huygens Mission. Hydrocarbons are also abundant in nebulae forming polycyclic aromatic hydrocarbon compounds, hydrocarbons are a primary energy source for current civilizations. The predominant use of hydrocarbons is as a fuel source. In their solid form, hydrocarbons take the form of asphalt, mixtures of volatile hydrocarbons are now used in preference to the chlorofluorocarbons as a propellant for aerosol sprays, due to chlorofluorocarbons impact on the ozone layer. Methane and ethane are gaseous at ambient temperatures and cannot be liquefied by pressure alone. Propane is however easily liquefied, and exists in propane bottles mostly as a liquid, butane is so easily liquefied that it provides a safe, volatile fuel for small pocket lighters
22.
-yne
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In chemistry, the suffix -yne is used to denote the presence of a triple bond. The suffix follows IUPAC nomenclature, and is used in organic chemistry. The position of unsaturation is indicated by a numerical locant immediately preceding the -yne suffix, locants are chosen to be as low as possible. -yne is also used as an infix to name substituent groups that are bound to the parent compound. This suffix arose as a form of the end of the word acetylene. The final -e disappears if it is followed by another suffix that starts with a vowel
23.
Alkyne
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In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. The simplest acyclic alkynes with only one bond and no other functional groups form a homologous series with the general chemical formula CnH2n−2. Alkynes are traditionally known as acetylenes, although the name also refers specifically to C2H2. Like other hydrocarbons, alkynes are generally hydrophobic but tend to be more reactive, alkynes are characteristically more unsaturated than alkenes. Thus they add two equivalents of bromine whereas an alkene adds only one equivalent in the reaction, in some reactions, alkynes are less reactive than alkenes. For example, in a molecule with an -ene and an -yne group, possible explanations involve the two π-bonds in the alkyne delocalising, which would reduce the energy of the π-system or the stability of the intermediates during the reaction. They show greater tendency to polymerize or oligomerize than alkenes do, the resulting polymers, called polyacetylenes are conjugated and can exhibit semiconducting properties. In acetylene, the H–C≡C bond angles are 180°, by virtue of this bond angle, alkynes are rod-like. The C≡C bond distance of 121 picometers is much shorter than the C=C distance in alkenes or the C–C bond in alkanes, the triple bond is very strong with a bond strength of 839 kJ/mol. The sigma bond contributes 369 kJ/mol, the first pi bond contributes 268 kJ/mol, bonding usually discussed in the context of molecular orbital theory, which recognizes the triple bond as arising from overlap of s and p orbitals. In the language of valence bond theory, the atoms in an alkyne bond are sp hybridized. Overlap of an sp orbital from each atom forms one sp–sp sigma bond, each p orbital on one atom overlaps one on the other atom, forming two pi bonds, giving a total of three bonds. The remaining sp orbital on each atom can form a bond to another atom. The two sp orbitals project on opposite sides of the carbon atom, internal alkynes feature carbon substituents on each acetylenic carbon. Symmetrical examples include diphenylacetylene and 3-hexyne, terminal alkynes have the formula RC2H. Terminal alkynes, like itself, are mildly acidic, with pKa values of around 25. They are far more acidic than alkenes and alkanes, which have pKa values of around 40 and 50, the acidic hydrogen on terminal alkynes can be replaced by a variety of groups resulting in halo-, silyl-, and alkoxoalkynes. The carbanions generated by deprotonation of terminal alkynes are called acetylides, in systematic chemical nomenclature, alkynes are named with the Greek prefix system without any additional letters
24.
Aromatic
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Aromatic molecules are very stable, and do not break apart easily to react with other substances. Organic compounds that are not aromatic are classified as aliphatic compounds—they might be cyclic, since the most common aromatic compounds are derivatives of benzene, the word “aromatic” occasionally refers informally to benzene derivatives, and so it was first defined. Nevertheless, many aromatic compounds exist. In living organisms, for example, the most common aromatic rings are the bases in RNA and DNA. An aromatic functional group or other substituent is called an aryl group, the earliest use of the term aromatic was in an article by August Wilhelm Hofmann in 1855. Hofmann used the term for a class of compounds, many of which have odors. In terms of the nature of the molecule, aromaticity describes a conjugated system often made of alternating single and double bonds in a ring. This configuration allows for the electrons in the pi system to be delocalized around the ring, increasing the molecules stability. The molecule cannot be represented by one structure, but rather a hybrid of different structures. These molecules cannot be found in one of these representations, with the longer single bonds in one location. Rather, the molecule exhibits bond lengths in between those of single and double bonds and this commonly seen model of aromatic rings, namely the idea that benzene was formed from a six-membered carbon ring with alternating single and double bonds, was developed by August Kekulé. The model for benzene consists of two forms, which corresponds to the double and single bonds superimposing to produce six one-and-a-half bonds. Benzene is a stable molecule than would be expected without accounting for charge delocalization. As is standard for resonance diagrams, the use of an arrow indicates that two structures are not distinct entities but merely hypothetical possibilities. Neither is a representation of the actual compound, which is best represented by a hybrid of these structures. A C=C bond is shorter than a C−C bond, but benzene is perfectly hexagonal—all six carbon–carbon bonds have the same length, intermediate between that of a single and that of a double bond. In a cyclic molecule with three alternating double bonds, cyclohexatriene, the length of the single bond would be 1.54 Å. However, in a molecule of benzene, the length of each of the bonds is 1.40 Å, a better representation is that of the circular π-bond, in which the electron density is evenly distributed through a π-bond above and below the ring
25.
Alicyclic compound
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An alicyclic compound is an organic compound that is both aliphatic and cyclic. They contain one or more all-carbon rings which may be saturated or unsaturated. Alicyclic compounds may have one or more aliphatic side chains attached, the simplest alicyclic compounds are the monocyclic cycloalkanes, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, and so on. Bicyclic alkanes include bicycloundecane, decalin, and housane, polycyclic alkanes include cubane, basketane, and tetrahedrane. Spiro compounds have two or more rings that are connected through only one carbon atom, the mode of ring-closing in the formation of many alicyclic compounds can be predicted by Baldwins rules. Otto Wallach, a German chemist, received the 1910 Nobel Prize in Chemistry for his work on alicyclic compounds, monocyclic cycloalkenes are cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, and so on. Bicyclic alkenes include norbornene and norbornadiene, isotoluenes are a prominent class of compounds with exocyclic double bonds. The placement of bonds in many alicyclic compounds can be predicted with Bredts rule
26.
Oxygen
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Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the group on the periodic table and is a highly reactive nonmetal. By mass, oxygen is the third-most abundant element in the universe, after hydrogen, at standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. This is an important part of the atmosphere and diatomic oxygen gas constitutes 20. 8% of the Earths atmosphere, additionally, as oxides the element makes up almost half of the Earths crust. Most of the mass of living organisms is oxygen as a component of water, conversely, oxygen is continuously replenished by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. Oxygen is too reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form of oxygen, ozone, strongly absorbs ultraviolet UVB radiation, but ozone is a pollutant near the surface where it is a by-product of smog. At low earth orbit altitudes, sufficient atomic oxygen is present to cause corrosion of spacecraft, the name oxygen was coined in 1777 by Antoine Lavoisier, whose experiments with oxygen helped to discredit the then-popular phlogiston theory of combustion and corrosion. One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work Pneumatica, Philo observed that inverting a vessel over a burning candle, Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass. Many centuries later Leonardo da Vinci built on Philos work by observing that a portion of air is consumed during combustion and respiration, Oxygen was discovered by the Polish alchemist Sendivogius, who considered it the philosophers stone. In the late 17th century, Robert Boyle proved that air is necessary for combustion, English chemist John Mayow refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus. From this he surmised that nitroaereus is consumed in both respiration and combustion, Mayow observed that antimony increased in weight when heated, and inferred that the nitroaereus must have combined with it. Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract De respiratione. Robert Hooke, Ole Borch, Mikhail Lomonosov, and Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element. This may have been in part due to the prevalence of the philosophy of combustion and corrosion called the phlogiston theory, which was then the favored explanation of those processes. Established in 1667 by the German alchemist J. J. Becher, one part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx. The fact that a substance like wood gains overall weight in burning was hidden by the buoyancy of the combustion products
27.
Ester
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In chemistry, esters are chemical compounds derived from an acid in which at least one –OH group is replaced by an –O–alkyl group. Usually, esters are derived from an acid and an alcohol. Glycerides, which are fatty acid esters of glycerol, are important esters in biology, being one of the classes of lipids. Esters with low weight are commonly used as fragrances and found in essential oils. Phosphoesters form the backbone of DNA molecules, nitrate esters, such as nitroglycerin, are known for their explosive properties, while polyesters are important plastics, with monomers linked by ester moieties. The word ester was coined in 1848 by German chemist Leopold Gmelin, probably as a contraction of the German Essigäther, ester names are derived from the parent alcohol and the parent acid, where the latter may be organic or inorganic. Esters derived from more complex carboxylic acids are, on the hand, more frequently named using the systematic IUPAC name. For example, the ester hexyl octanoate, also known under the trivial name hexyl caprylate, has the formula CH36CO25CH3, the chemical formulas of organic esters usually take the form RCO2R′, where R and R′ are the hydrocarbon parts of the carboxylic acid and the alcohol, respectively. For example, butyl acetate, derived from butanol and acetic acid would be written CH3CO2C4H9, alternative presentations are common including BuOAc and CH3COOC4H9. Cyclic esters are called lactones, regardless of whether they are derived from an organic or an inorganic acid, one example of a lactone is γ-valerolactone. An uncommon class of organic esters are the orthoesters, which have the formula RC3, triethylorthoformate is derived, in terms of its name from orthoformic acid and ethanol. Esters can also be derived from an acid and an alcohol. For example, triphenyl phosphate is the derived from phosphoric acid. Organic carbonates are derived from acid, for example, ethylene carbonate is derived from carbonic acid. So far an alcohol and inorganic acid are linked via oxygen atoms, in corollary, boron features borinic esters, boronic esters, and borates. As oxygen is a group 16 chemical element, sulfur atoms can replace some oxygen atoms in carbon–oxygen–central inorganic atom covalent bonds of an ester, esters contain a carbonyl center, which gives rise to 120 ° C–C–O and O–C–O angles. Unlike amides, esters are structurally flexible functional groups because rotation about the C–O–C bonds has a low barrier and their flexibility and low polarity is manifested in their physical properties, they tend to be less rigid and more volatile than the corresponding amides. The pKa of the alpha-hydrogens on esters is around 25, the preference for the Z conformation is influenced by the nature of the substituents and solvent, if present
28.
Carboxylic acid
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A carboxylic acid /ˌkɑːrbɒkˈsɪlɪk/ is an organic compound that contains a carboxyl group. The general formula of an acid is R–COOH, with R referring to the rest of the molecule. Carboxylic acids occur widely and include the amino acids and acetic acid, salts and esters of carboxylic acids are called carboxylates. When a carboxyl group is deprotonated, its conjugate base forms a carboxylate anion, carboxylate ions are resonance-stabilized, and this increased stability makes carboxylic acids more acidic than alcohols. Carboxylic acids can be seen as reduced or alkylated forms of the Lewis acid carbon dioxide, carboxylic acids are commonly identified using their trivial names, and usually have the suffix -ic acid. IUPAC-recommended names also exist, in system, carboxylic acids have an -oic acid suffix. For example, butyric acid is butanoic acid by IUPAC guidelines, the -oic acid nomenclature detail is based on the name of the previously-known chemical benzoic acid. Alternately, it can be named as a carboxy or carboxylic acid substituent on another parent structure, for example, 2-carboxyfuran. The carboxylate anion of an acid is usually named with the suffix -ate, in keeping with the general pattern of -ic acid and -ate for a conjugate acid and its conjugate base. For example, the base of acetic acid is acetate. The radical •COOH has only a fleeting existence. The acid dissociation constant of •COOH has been measured using electron paramagnetic resonance spectroscopy, the carboxyl group tends to dimerise to form oxalic acid. Because they are both hydrogen-bond acceptors and hydrogen-bond donors, they participate in hydrogen bonding. Together the hydroxyl and carbonyl group forms the functional group carboxyl, carboxylic acids usually exist as dimeric pairs in nonpolar media due to their tendency to self-associate. Smaller carboxylic acids are soluble in water, whereas higher carboxylic acids are less due to the increasing hydrophobic nature of the alkyl chain. These longer chain acids tend to be soluble in less-polar solvents such as ethers. Carboxylic acids tend to have higher boiling points than water, not only because of their surface area. Carboxylic acids tend to evaporate or boil as these dimers, for boiling to occur, either the dimer bonds must be broken or the entire dimer arrangement must be vaporised, both of which increase the enthalpy of vaporization requirements significantly
29.
Alcohol
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In chemistry, an alcohol is any organic compound in which the hydroxyl functional group is bound to a saturated carbon atom. The term alcohol originally referred to the alcohol ethanol, the predominant alcohol in alcoholic beverages. The suffix -ol in non-systematic names also typically indicates that the substance includes a functional group and, so. But many substances, particularly sugars contain hydroxyl functional groups without using the suffix, an important class of alcohols, of which methanol and ethanol are the simplest members is the saturated straight chain alcohols, the general formula for which is CnH2n+1OH. The word alcohol is from the Arabic kohl, a used as an eyeliner. Al- is the Arabic definite article, equivalent to the in English, alcohol was originally used for the very fine powder produced by the sublimation of the natural mineral stibnite to form antimony trisulfide Sb 2S3, hence the essence or spirit of this substance. It was used as an antiseptic, eyeliner, and cosmetic, the meaning of alcohol was extended to distilled substances in general, and then narrowed to ethanol, when spirits as a synonym for hard liquor. Bartholomew Traheron, in his 1543 translation of John of Vigo, Vigo wrote, the barbarous auctours use alcohol, or alcofoll, for moost fine poudre. The 1657 Lexicon Chymicum, by William Johnson glosses the word as antimonium sive stibium, by extension, the word came to refer to any fluid obtained by distillation, including alcohol of wine, the distilled essence of wine. Libavius in Alchymia refers to vini alcohol vel vinum alcalisatum, Johnson glosses alcohol vini as quando omnis superfluitas vini a vino separatur, ita ut accensum ardeat donec totum consumatur, nihilque fæcum aut phlegmatis in fundo remaneat. The words meaning became restricted to spirit of wine in the 18th century and was extended to the class of substances so-called as alcohols in modern chemistry after 1850, the term ethanol was invented 1892, based on combining the word ethane with ol the last part of alcohol. In the IUPAC system, in naming simple alcohols, the name of the alkane chain loses the terminal e and adds ol, e. g. as in methanol and ethanol. When necessary, the position of the group is indicated by a number between the alkane name and the ol, propan-1-ol for CH 3CH 2CH 2OH, propan-2-ol for CH 3CHCH3. If a higher priority group is present, then the prefix hydroxy is used, in other less formal contexts, an alcohol is often called with the name of the corresponding alkyl group followed by the word alcohol, e. g. methyl alcohol, ethyl alcohol. Propyl alcohol may be n-propyl alcohol or isopropyl alcohol, depending on whether the group is bonded to the end or middle carbon on the straight propane chain. As described under systematic naming, if another group on the molecule takes priority, Alcohols are then classified into primary, secondary, and tertiary, based upon the number of carbon atoms connected to the carbon atom that bears the hydroxyl functional group. The primary alcohols have general formulas RCH2OH, the simplest primary alcohol is methanol, for which R=H, and the next is ethanol, for which R=CH3, the methyl group. Secondary alcohols are those of the form RRCHOH, the simplest of which is 2-propanol, for the tertiary alcohols the general form is RRRCOH
30.
Nitrogen
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Nitrogen is a chemical element with symbol N and atomic number 7. It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772, although Carl Wilhelm Scheele and Henry Cavendish had independently done so at about the same time, Rutherford is generally accorded the credit because his work was published first. Nitrogen is the lightest member of group 15 of the periodic table, the name comes from the Greek πνίγειν to choke, directly referencing nitrogens asphyxiating properties. It is an element in the universe, estimated at about seventh in total abundance in the Milky Way. At standard temperature and pressure, two atoms of the element bind to form dinitrogen, a colourless and odorless diatomic gas with the formula N2, dinitrogen forms about 78% of Earths atmosphere, making it the most abundant uncombined element. Nitrogen occurs in all organisms, primarily in amino acids, in the nucleic acids, the human body contains about 3% nitrogen by mass, the fourth most abundant element in the body after oxygen, carbon, and hydrogen. The nitrogen cycle describes movement of the element from the air, into the biosphere and organic compounds, many industrially important compounds, such as ammonia, nitric acid, organic nitrates, and cyanides, contain nitrogen. The extremely strong bond in elemental nitrogen, the second strongest bond in any diatomic molecule. Synthetically produced ammonia and nitrates are key industrial fertilisers, and fertiliser nitrates are key pollutants in the eutrophication of water systems. Apart from its use in fertilisers and energy-stores, nitrogen is a constituent of organic compounds as diverse as Kevlar used in high-strength fabric, Nitrogen is a constituent of every major pharmacological drug class, including antibiotics. Many notable nitrogen-containing drugs, such as the caffeine and morphine or the synthetic amphetamines. Nitrogen compounds have a long history, ammonium chloride having been known to Herodotus. They were well known by the Middle Ages, alchemists knew nitric acid as aqua fortis, as well as other nitrogen compounds such as ammonium salts and nitrate salts. The mixture of nitric and hydrochloric acids was known as aqua regia, celebrated for its ability to dissolve gold, the discovery of nitrogen is attributed to the Scottish physician Daniel Rutherford in 1772, who called it noxious air. Though he did not recognise it as a different chemical substance, he clearly distinguished it from Joseph Blacks fixed air. The fact that there was a component of air that does not support combustion was clear to Rutherford, Nitrogen was also studied at about the same time by Carl Wilhelm Scheele, Henry Cavendish, and Joseph Priestley, who referred to it as burnt air or phlogisticated air. Nitrogen gas was inert enough that Antoine Lavoisier referred to it as air or azote, from the Greek word άζωτικός. In an atmosphere of nitrogen, animals died and flames were extinguished
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Alkaloid
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Alkaloids are a group of naturally occurring chemical compounds that mostly contain basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties, some synthetic compounds of similar structure are also termed alkaloids. In addition to carbon, hydrogen and nitrogen, alkaloids may also contain oxygen, sulfur and, more rarely, other such as chlorine, bromine. Alkaloids are produced by a variety of organisms including bacteria, fungi, plants. They can be purified from crude extracts of these organisms by acid-base extraction, many have found use in traditional or modern medicine, or as starting points for drug discovery. Other alkaloids possess psychotropic and stimulant activities, and have used in entheogenic rituals or as recreational drugs. Although alkaloids act on a diversity of systems in humans and other animals. The boundary between alkaloids and other nitrogen-containing natural compounds is not clear-cut, Compounds like amino acid peptides, proteins, nucleotides, nucleic acid, amines, and antibiotics are usually not called alkaloids. Natural compounds containing nitrogen in the position are usually classified as amines rather than as alkaloids. Some authors, however, consider alkaloids a special case of amines, the name alkaloids was introduced in 1819 by the German chemist Carl Friedrich Wilhelm Meißner, and is derived from late Latin root Latin, alkali and the suffix Greek, -οειδής – like. However, the term came into use only after the publication of a review article by Oscar Jacobsen in the chemical dictionary of Albert Ladenburg in the 1880s. There is no method of naming alkaloids. Many individual names are formed by adding the suffix ine to the species or genus name, for example, atropine is isolated from the plant Atropa belladonna, strychnine is obtained from the seed of Strychnine tree. If several alkaloids are extracted from one plant then their names often contain suffixes idine, anine, aline, inine etc. There are also at least 86 alkaloids whose names contain the root vin because they are extracted from plants such as Vinca rosea. Alkaloid-containing plants have been used by humans since ancient times for therapeutic, for example, medicinal plants have been known in the Mesopotamia at least around 2000 BC. The Odyssey of Homer referred to a given to Helen by the Egyptian queen. It is believed that the gift was an opium-containing drug, a Chinese book on houseplants written in 1st–3rd centuries BC mentioned a medical use of Ephedra and opium poppies
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Aza-
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The prefix aza- is used in organic chemistry to form names of organic compounds where a carbon atom is replaced by a nitrogen atom. The related term refers to when a nitrogen is removed and, usually. Sometimes a number between hyphens is inserted before it to state which atom the nitrogen atom replaces and it arose by shortening the word azote, which is an obsolete name for nitrogen in the English language and occurs in current French usage, meaning Nitrogen. This prefix is part of the Hantzsch–Widman nomenclature
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Sulfur
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Sulfur or sulphur is a chemical element with symbol S and atomic number 16. It is abundant, multivalent, and nonmetallic, under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a yellow crystalline solid at room temperature. Chemically, sulfur reacts with all elements except for gold, platinum, iridium, tellurium, though sometimes found in pure, native form, sulfur usually occurs as sulfide and sulfate minerals. Being abundant in native form, sulfur was known in ancient times, being mentioned for its uses in ancient India, ancient Greece, China, in the Bible, sulfur is called brimstone. Today, almost all elemental sulfur is produced as a byproduct of removing sulfur-containing contaminants from natural gas, the greatest commercial use of the element is the production of sulfuric acid for sulfate and phosphate fertilizers, and other chemical processes. The element sulfur is used in matches, insecticides, and fungicides, many sulfur compounds are odoriferous, and the smells of odorized natural gas, skunk scent, grapefruit, and garlic are due to organosulfur compounds. Hydrogen sulfide gives the characteristic odor to rotting eggs and other biological processes, sulfur is an essential element for all life, but almost always in the form of organosulfur compounds or metal sulfides. Three amino acids and two vitamins are organosulfur compounds, many cofactors also contain sulfur including glutathione and thioredoxin and iron–sulfur proteins. Disulfides, S–S bonds, confer mechanical strength and insolubility of the keratin, found in outer skin, hair. Sulfur is one of the chemical elements needed for biochemical functioning and is an elemental macronutrient for all organisms. Sulfur is derived from the Latin word sulpur, which was Hellenized to sulphur, the spelling sulfur appears toward the end of the Classical period. In 12th-century Anglo-French, it was sulfre, in the 14th century the Latin ph was restored, for sulphre, the parallel f~ph spellings continued in Britain until the 19th century, when the word was standardized as sulphur. Sulfur was the form chosen in the United States, whereas Canada uses both, the IUPAC adopted the spelling sulfur in 1990, as did the Nomenclature Committee of the Royal Society of Chemistry in 1992, restoring the spelling sulfur to Britain. Sulfur forms polyatomic molecules with different chemical formulas, the best-known allotrope being octasulfur, cyclo-S8. The point group of cyclo-S8 is D4d and its dipole moment is 0 D. Octasulfur is a soft, bright-yellow solid that is odorless and it melts at 115.21 °C, boils at 444.6 °C and sublimes easily. At 95.2 °C, below its melting temperature, cyclo-octasulfur changes from α-octasulfur to the β-polymorph, the structure of the S8 ring is virtually unchanged by this phase change, which affects the intermolecular interactions. At higher temperatures, the viscosity decreases as depolymerization occurs, molten sulfur assumes a dark red color above 200 °C
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Enzyme
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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
