In aldehyde sugars, the carbonyl group is at the end of the carbon skeleton, while in the ketone sugars, the carbonyl group is within the carbon skeleton. Fructose is classified as a monosaccharide, the most important ketose sugar, a hexose, and is a reducing sugar. Sucrose is a disaccharide sugar, meaning it is made up of two monosaccharide sugar units.
In the case of sucrose, the two units are glucose and fructose. The name sucrose comes from the French word for sugar: sucre. Disaccharides are formed when two monosaccharides join together by the dehydration synthesis reaction resulting in a glycosidic bond between the two monosaccharide molecules.
The reaction produces water as a side product. Monosaccharides exhibit aldose-ketose isomerism. Sugar with a keto groups is called a ketose and that with an aldehyde group is called an aldose. Glucose is an aldose since there is a potential aldehyde group in position 1 of glucose. Fructose is a ketose since it has a potential keto group in position 2. Glyceraldehyde is produced from the action of the enzyme glyceraldehyde dehydrogenase, which converts glycerol to glyceraldehyde using NADP as a cofactor.
When present at sufficiently high levels, glyceraldehyde can be a cytotoxin and a mutagen. Many sugar molecules linked together is a polysaccharide. Starch, therefore, is a polysaccharide. Specifically, starch is composed of the sugar glucose. Corn syrup is primarily glucose. Glucose is one of the primary molecules which serve as energy sources for plants and animals.
It is found in the sap of plants, and is found in the human bloodstream where it is referred to as "blood sugar". Monosaccharides can be classified by the number x of carbon atoms they contain: triose 3 , tetrose 4 , pentose 5 , hexose 6 , heptose 7 , and so on. The most important monosaccharide, glucose, is a hexose. They differ only in the direction that -H and -OH groups point on carbon 1 See the jmol images below. When alpha-glucose molecules are joined chemically to form a polymer starch is formed.
When beta-glucose molecules are joined to form a polymer cellulose is formed. Pyranose is a collective term for saccharides that have a chemical structure that includes a six-membered ring consisting of five carbon atoms and one oxygen atom. There may be other carbons external to the ring. The glucose and fructose units are joined by an acetal oxygen bridge in the alpha-1 on the glucose and beta-2 on the fructose orientation. The structure is easy to recognize because it contains the six member ring of glucose and the five member ring of fructose.
To recognize glucose look for the horizontal projection of the -OH on carbon 4. See details on the galactose page towards the bottom. The alpha-1, beta-2 acetal is really part of a double acetal, since the two monosaccharides are joined at the hemiacetal alpha-1 of glucose and the hemiketal beta-2 of the fructose.
There are no hemiacetals remaining in the sucrose and therefore sucrose is a non-reducing sugar. Sugar and Tooth Decay Sugar Processing:. Sugar or more specifically sucrose is a carbohydrate that occurs naturally in every fruit and vegetable. It is the major product of photosynthesis, the process by which plants transform the sun's energy into food. Sugar occurs in greatest quantities in sugar cane and sugar beets from which it is separated for commercial use.
In the first stage of processing the natural sugar stored in the cane stalk or beet root is separated from the rest of the plant material by physical methods. For sugar cane, this is accomplished by: a pressing the cane to extract the juice containing the sugar b boiling the juice until it begins to thicken and sugar begins to crystallize c spinning the sugar crystals in a centrifuge to remove the syrup, producing raw sugar; the raw sugar still contains many impurities d shipping the raw sugar to a refinery where it is washed and filtered to remove remaining non-sugar ingredients and color e crystallizing, drying and packaging the refined sugar.
Beet sugar processing is similar, but it is done in one continuous process without the raw sugar stage. The sugar beets are washed, sliced and soaked in hot water to separate the sugar-containing juice from the beet fiber. The sugar-laden juice is purified, filtered, concentrated and dried in a series of steps similar to cane sugar processing.
The disacharrides Sucrose and Lactose in their ring forms" color white color blue [ Let's look at sucrose first. The carbon labeled 1 is the anomeric carbon color blue [ The cool thing about anomeric carbons is that depending on their stereochemistry two color red "anomers" isomers can exist - the color red [alpha] or the color red [beta] form. Related questions How do I determine the molecular shape of a molecule? What is the lewis structure for co2? What is the lewis structure for hcn?
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