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
