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Disaccharide
A DISACCHARIDE (also called a DOUBLE SUGAR or BIOSE ) is the sugar formed when two monosaccharides (simple sugars) are joined by glycosidic linkage. Like monosaccharides, disaccharides are soluble in water. Three common examples are sucrose , lactose , and maltose . Disaccharides are one of the four chemical groupings of carbohydrates (monosaccharides , disaccharides, oligosaccharides , and polysaccharides ). The most common types of disaccharides—sucrose , lactose , and maltose —have twelve carbon atoms, with the general formula C12H22O11. The differences in these disaccharides are due to atomic arrangements within the molecule. The joining of simple sugars into a double sugar happens by a condensation reaction , which involves the elimination of a water molecule from the functional groups only. Breaking apart a double sugar into its two simple sugars is accomplished by hydrolysis with the help of a type of enzyme called a disaccharidase
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Glycoside
In chemistry , a GLYCOSIDE /ˈɡlaɪkəsaɪd/ is a molecule in which a sugar is bound to another functional group via a glycosidic bond . Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by enzyme hydrolysis , which causes the sugar part to be broken off, making the chemical available for use. Many such plant glycosides are used as medications . In animals and humans, poisons are often bound to sugar molecules as part of their elimination from the body. In formal terms, a glycoside is any molecule in which a sugar group is bonded through its anomeric carbon to another group via a glycosidic bond . Glycosides can be linked by an O- (an O-glycoside), N- (a glycosylamine ), S-(a thioglycoside), or C- (a C-glycoside) glycosidic bond. According to the IUPAC
IUPAC
, the name "C-glycoside" is a misnomer; the preferred term is "C-glycosyl compound"
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Acetal
An ACETAL is a functional group with the following connectivity R2C(OR')2, where both R' groups are organic fragments. The central carbon atom has four bonds to it, and is therefore saturated and has tetrahedral geometry . The two R'O groups may be equivalent to each other or not. The two R groups can be equivalent to each other (a "symmetric acetal") or not (a "mixed acetal"), and one or both can even be hydrogen atoms rather than organic fragments. Acetals are formed from and convertible to carbonyl compounds (aldehydes or ketones R2C=O). The term KETAL is sometimes used to identify structures associated with ketones rather than aldehydes and, historically, the term acetal was used specifically for the aldehyde cases. Formation of an acetal occurs when the hydroxyl group of a hemiacetal becomes protonated and is lost as water. The carbocation that is produced is then rapidly attacked by a molecule of alcohol . Loss of the proton from the attached alcohol gives the acetal
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Aldehyde
An ALDEHYDE /ˈældᵻhaɪd/ or ALKANAL is an organic compound containing a functional group with the structure −CHO, consisting of a carbonyl center (a carbon double-bonded to oxygen) with the carbon atom also bonded to hydrogen and to an R group , which is any generic alkyl or side chain. The group—without R—is the ALDEHYDE GROUP, also known as the FORMYL GROUP. Aldehydes are common in organic chemistry . Many fragrances are aldehydes
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Hemiacetal
HEMIACETALS and HEMIKETALS are compounds that are derived from aldehydes and ketones respectively. The Greek word hèmi means half. These compounds are formed by formal addition of an alcohol to the carbonyl group. When the alcohol group is replaced by a second alkoxy group , an acetal or a ketal , respectively, is formed. CONTENTS* 1 Formula and formation * 1.1 Cyclic hemiacetals and hemiketals * 2 Synthesis * 3 Reactions * 4 See also * 5 References FORMULA AND FORMATION Above: 1-ethoxybutan-1-ol, a hemiacetal. Below: 1,1-diethoxybutan, an acetal The general formula of a hemiacetal is R1R2C(OH)OR, where R1 or R2 is often hydrogen and R (bonded to O) is not hydrogen. While in the IUPAC
IUPAC
definition of a hemiacetal R1 or R2 may or may not be a hydrogen, in a hemiketal none of the R-groups is an H. Hemiketals are regarded as hemiacetals that have no R-groups being H, thus a subclass of the hemiacetals
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Sucrase
SUCRASE is a digestive enzyme secreted in the small intestine. Sucrase enzymes are located on the brush border of the small intestine. The enzymes catalyze the hydrolysis of sucrose to fructose and glucose . The sucrase enzyme invertase , which occurs more commonly in plants, also hydrolyzes sucrose but by a different mechanism. CONTENTS * 1 Types * 2 Physiology * 3 Use in chemical analysis * 4 References * 5 External links TYPES * EC 3.2.1.10 is sucrase-isomaltase * EC 3.2.1.26 is invertase * EC 3.2.1.48 is sucrose alpha-glucosidase PHYSIOLOGYSucrose intolerance (also known as congenital sucrase-isomaltase deficiency (CSID), genetic sucrase-isomaltase deficiency (GSID), or sucrase-isomaltase deficiency) occurs when sucrase is not secreted in the small intestine. With sucrose intolerance, the result of consuming sucrose is excess gas production and often diarrhea and malabsorption
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Radical (chemistry)
In chemistry , a RADICAL (more precisely, a FREE RADICAL) is an atom , molecule , or ion that has an unpaired valence electron . With some exceptions, these unpaired electrons make free radicals highly chemically reactive towards other substances, or even towards themselves: their molecules will often spontaneously dimerize or polymerize if they come in contact with each other. Most radicals are reasonably stable only at very low concentrations in inert media or in a vacuum. A notable example of a free radical is the hydroxyl radical (HO•), a molecule that has one unpaired electron on the oxygen atom. Two other examples are triplet oxygen and triplet carbene (:CH 2) which have two unpaired electrons. In contrast, the hydroxyl anion (HO− ) is not a radical, since the unpaired electron is resolved by the addition of an electron; singlet oxygen and singlet carbene are not radicals as the two electrons are paired
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Hydrogen Atom
Hydrogen
Hydrogen
atom Full table GENERAL Name , symbol protium,1H Neutrons 0 Protons 1 NUCLIDE DATA Natural abundance 99.985% Isotope
Isotope
mass 1.007825 u Spin 1/2 Excess energy 7288.969± 0.001 keV Binding energy 0.000± 0.0000 keV Depiction of a hydrogen atom showing the diameter as about twice the Bohr model
Bohr model
radius. (Image not to scale) A HYDROGEN ATOM is an atom of the chemical element hydrogen . The electrically neutral atom contains a single positively charged proton and a single negatively charged electron bound to the nucleus by the Coulomb force
Coulomb force
. ATOMIC HYDROGEN constitutes about 75% of the baryonic mass of the universe. In everyday life on Earth, isolated hydrogen atoms (called "atomic hydrogen") are extremely rare
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Diastereoisomer
DIASTEREOMERS (sometimes called DIASTEREOISOMERS) are a type of a stereoisomer . Diastereomerism occurs when two or more stereoisomers of a compound have different configurations at one or more (but not all) of the equivalent (related) stereocenters and are not mirror images of each other. When two diastereoisomers differ from each other at only one stereocenter they are epimers . Each stereocenter gives rise to two different configurations and thus increases the number of stereoisomers by a factor of two. Diastereomers differ from enantiomers in that the latter are pairs of stereoisomers that differ in all stereocenters and are therefore mirror images of one another. Enantiomers of a compound with more than one stereocenter are also diastereomers of the other stereoisomers of that compound that are not their mirror image. Diastereomers have different physical properties (unlike enantiomers) and different chemical reactivity
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Glucosamine
GLUCOSAMINE (C6H13NO5) is an amino sugar and a prominent precursor in the biochemical synthesis of glycosylated proteins and lipids. Glucosamine
Glucosamine
is part of the structure of the polysaccharides chitosan and chitin , which compose the exoskeletons of crustaceans and other arthropods , as well as the cell walls of fungi and many higher organisms. Glucosamine
Glucosamine
is one of the most abundant monosaccharides . It is produced commercially by the hydrolysis of crustacean exoskeletons or, less commonly, by fermentation of a grain such as corn or wheat. Evidence for the effectiveness of glucosamine supplements is mixed. In the United States, it is one of the most common non-vitamin, non-mineral, dietary supplements used by adults
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Stereochemistry
STEREOCHEMISTRY, a subdiscipline of chemistry , involves the study of the relative spatial arrangement of atoms that form the structure of molecules and their manipulation. The study of stereochemistry focuses on stereoisomers , which by definition have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in space. For this reason, it is also known as 3D chemistry—the prefix "stereo-" means "three-dimensionality". An important branch of stereochemistry is the study of chiral molecules. Stereochemistry
Stereochemistry
spans the entire spectrum of organic , inorganic , biological , physical and especially supramolecular chemistry
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Monomer
A MONOMER (/ˈmɒnəmər/ MON-ə-mər ) (mono-, "one" + -mer, "part") is a molecule that, as a unit, binds chemically or supramolecularly to other molecules to form a supramolecular polymer . Large numbers of monomer units combine to form polymers in a process called polymerization . Molecules of a small number of monomer units (up to a few dozen) are called oligomers . The term "monomeric protein " may also be used to describe one of the proteins making up a multiprotein complex
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Proton
6973167262189800000♠1.672621898(21)×10−27 kg 7002938272081300000♠938.2720813(58) MeV/c2 7000100727646687900♠1.007276466879(91) u MEAN LIFETIME > 7036662709600000000♠2.1×1029 years (stable) ELECTRIC CHARGE 6981160217648700000♠+1 e 6981160217662079999♠1.6021766208(98)×10−19 C CHARGE RADIUS 6999875100000000000♠0.8751(61) fm ELECTRIC DIPOLE MOMENT < 6976540000000000000♠5.4×10−24 e⋅cm ELECTRIC POLARIZABILITY 6997119999999999999♠1.20(6)×10−3 fm3 MAGNETIC MOMENT 6974141060678730000♠1.4106067873(97)×10−26 J ⋅T −1 6997152103220530000♠1.5210322053(46)×10−3 μB 7000279284735079999♠2.7928473508(85) μN MAGNETIC POLARIZABILITY 6996190000000000000♠1.9(5)×10−4 fm3 SPIN 1/2 ISOSPIN 1/2 PARITY +1 CONDENSED I (J P ) = 1/2(1/2+)A PROTON is a subatomic particle , symbol p or p+ , with a positive electric charge of +1e elementary charge and mass slightly less than that of a neutron
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Enzyme
ENZYMES /ˈɛnzaɪmz/ are macromolecular biological catalysts . Enzymes accelerate chemical reactions . The molecules upon which enzymes may act are called substrates and the enzyme converts the substrates into different molecules known as products . Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. :8.1 Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called enzymology and a new field of pseudoenzyme analysis has recently grown up, recognising that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Most enzymes are proteins , although a few are catalytic RNA molecules . The latter are called ribozymes
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Reducing Agent
A REDUCING AGENT (also called a REDUCTANT or REDUCER) is an element (such as calcium) or compound that loses (or "donates") an electron to another chemical species in a redox chemical reaction. Since the reducing agent is losing electrons, it is said to have been oxidized. If any chemical is an electron donor (reducing agent), another must be an electron recipient (oxidizing agent ). A reducing agent is oxidized because it loses electrons in the redox reaction. Thus reducers are "oxidized" by oxidizers and oxidizers are "reduced" by reducers; reducers are by themselves reduced (have more electrons) and oxidizers are by themselves oxidized (have fewer electrons). A reducing agent typically is in one of its lower possible oxidation states and is known as the electron donor. Examples of reducing agents include the earth metals, formic acid , and sulfite compounds
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Carbon
CARBON (from Latin
Latin
: carbo "coal") 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 . It belongs to group 14 of the periodic table. Three isotopes occur naturally, 12C and 13C being stable, while 14C is a radionuclide , decaying with a half-life of about 5,730 years. Carbon
Carbon
is one of the few elements known since antiquity . Carbon
Carbon
is the 15th most abundant element in the Earth\'s crust , and the fourth most abundant element in the universe by mass after hydrogen , helium , and oxygen . Carbon's abundance, its unique diversity of organic compounds , and its unusual ability to form polymers at the temperatures commonly encountered on Earth
Earth
enables this element to serve as a common element of all known life
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