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Monosaccharides are the simplest units of carbohydrates and the simplest form of sugar. If the carbonyl is at position 1 (that is, n or m is zero), the molecule begins with a formyl group H(C=O)− and is technically an aldehyde. In that case, the compound is termed an aldose.
The table shows all aldoses with 3 to 6 carbon atoms, and a few ketoses. For chiral molecules, only the ' D-' form (with the next-to-last hydroxyl on the right side) is shown; the corresponding forms have mirror-image structures. Some of these monosaccharides are only synthetically prepared in the laboratory and not found in nature.
In these compounds, hydrogen can form in the +1 and -1 oxidation states. Hydrogen can form compounds both ionically and in covalent substances. It is a part of many organic compounds such as hydrocarbons as well as water and other organic substances. The H + ion is often called a proton because it has one proton and no electrons, although the ...
Compound sugars, also called disaccharides or double sugars, are molecules made of two bonded monosaccharides; common examples are sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (two molecules of glucose). White sugar is a refined form of sucrose. In the body, compound sugars are hydrolysed into simple sugars.
The conventional numbering of the carbons in the closed form is the same as in the open-chain form. If the sugar is an aldohexose, with the carbonyl in position 1, the reaction may involve the hydroxyl on carbon 4 or carbon 5, creating a hemiacetal with five- or six-membered ring, respectively.
Thus the structure of the linear form is H–(CHOH) x –C(=O)–(CHOH) 4-x –H, where x is 0, 1, or 2. The term "pentose" sometimes is assumed to include deoxypentoses, such as deoxyribose: compounds with general formula C 5 H 10 O 5-y that can be described as derived from pentoses by replacement of one or more hydroxyl groups with hydrogen ...
[5] [7] The naturally occurring form is d-glucose, while its stereoisomer l-glucose is produced synthetically in comparatively small amounts and is less biologically active. [7] Glucose is a monosaccharide containing six carbon atoms and an aldehyde group, and is therefore an aldohexose. The glucose molecule can exist in an open-chain (acyclic ...
An oligosaccharide has both a reducing and a non-reducing end. The reducing end of an oligosaccharide is the monosaccharide residue with hemiacetal functionality, thereby capable of reducing the Tollens’ reagent, while the non-reducing end is the monosaccharide residue in acetal form, thus incapable of reducing the Tollens’ reagent. [2]