Test For Carbohydrates

Topics: Carbohydrate, Glucose, Disaccharide Pages: 8 (4189 words) Published: October 31, 2014

Why do many proteins give positive result for Molisch’s test? Because many proteins have carbohydrate components in their structures.From what other sources are pentoses obtained? Arabinose is obtained from gum Arabic

Xylose is derived from wood gum
How would you test milk in a milk chocolate bar?
Music acid test
How can Selewanoff’s test be used to distinguish fructose from sucrose? Based on time reactions
*Ketoses are easily dehydrated
5. Of what use is Barfoed’s test in identifying an unknown sugar? It is used to distinguish monosaccharide from disaccharide wherein monosaccharide reduces Cu++ with in five minutes while disaccharide takes a longer time What is the chemical name and formula of the ppt. obtained as positive result in Benedicts and Barfoeds test? Cuprous Oxide

From Wikipedia, the free encyclopedia

Lactose is a disaccharide found in milk. It consists of a molecule of D-galactose and a molecule of D-glucosebonded by beta-1-4 glycosidic linkage. It has a formula of C12H22O11. A carbohydrate is a large biological molecule, or macromolecule, consisting of carbon (C), hydrogen (H), and oxygen (O) atoms, usually with a hydrogen:oxygen atom ratio of 2:1 (as in water); in other words, with the empirical formula Cm(H2O)n(where m could be different from n).[1] Some exceptions exist; for example, deoxyribose, a sugar component of DNA, HYPERLINK "http://en.wikipedia.org/wiki/Carbohydrate" \l "cite_note-2" [2] has the empirical formula C5H10O4.[3] Carbohydrates are technically hydrates of carbon;[4] structurally it is more accurate to view them as polyhydroxy aldehydes and ketones.[5]The term is most common in biochemistry, where it is a synonym of saccharide. The carbohydrates (saccharides) are divided into four chemical groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides. In general, the monosaccharides and disaccharides, which are smaller (lower molecular weight) carbohydrates, are commonly referred to assugars.[6] The word saccharide comes from the Greek word σάκχαρον (sákkharon), meaning "sugar." While the scientific nomenclature of carbohydrates is complex, the names of the monosaccharides and disaccharides very often end in the suffix -ose. For example, grape sugar is the monosaccharide glucose, cane sugar is the disaccharide sucrose, and milk sugar is the disaccharide lactose (see illustration). Carbohydrates perform numerous roles in living organisms. Polysaccharides serve for the storage of energy (e.g., starch and glycogen), and as structural components (e.g., cellulosein plants and chitin in arthropods). The 5-carbon monosaccharide ribose is an important component of coenzymes (e.g., ATP, FAD, and NAD) and the backbone of the genetic molecule known as RNA. The related deoxyribose is a component of DNA. Saccharides and their derivatives include many other important biomolecules that play key roles in theimmune system, fertilization, preventing pathogenesis, blood clotting, and development.[7]In food science and in many informal contexts, the term carbohydrate often means any food that is particularly rich in the complex carbohydrate starch (such as cereals, bread, andpasta) or simple carbohydrates, such as sugar (found in candy, jams, and desserts). Contents

1 Structure2 Monosaccharides2.1 Classification of monosaccharides2.2 Ring-straight chain isomerism2.3 Use in living organisms3 Disaccharides4 Nutrition4.1 Classification5 Metabolism5.1 Catabolism6 Carbohydrate chemistry7 See also8 References9 External linksStructure[ HYPERLINK "http://en.wikipedia.org/w/index.php?title=Carbohydrate&action=edit§ion=1" \o "Edit section: Structure" edit] Formerly the name "carbohydrate" was used in chemistry for any compound with the formula Cm (H2O) n. Following this definition, some chemists considered formaldehyde (CH2O) to be the simplest carbohydrate, HYPERLINK "http://en.wikipedia.org/wiki/Carbohydrate" \l "cite_note-coulter-8"...

References: edit]
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Jump up^ National Institute of Standards and Technology (2011). "Material Measurement Library D-erythro-Pentose, 2-deoxy-". nist.gov.
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Jump up^ Pigman, Ward; Anet, E.F.L.J. (1972). "Chapter 4: Mutarotations and Actions of Acids and Bases". In Pigman and Horton. The Carbohydrates: Chemistry and Biochemistry Vol 1A(2nd ed.). San Diego: Academic Press. pp. 165–194.
Jump up^ Park, Y; Subar, AF; Hollenbeck, A; Schatzkin, A (2011). "Dietary fiber intake and mortality in the NIH-AARP diet and health study". Archives of Internal Medicine 171 (12): 1061–8.doi:10.1001/archinternmed.2011.18. PMC 3513325. PMID 21321288.
Jump up^ Food and Nutrition Board (2002/2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, D.C.: The National Academies Press. Page 769. ISBN 0-309-08537-3.
Jump up^ Joint WHO/FAO expert consultation (2003). [2] (PDF). Geneva: World Health Organization. pp. 55–56. ISBN 92-4-120916-X.
Jump up^ Joint WHO/FAO expert consultation (1998), Carbohydrates in human nutrition, chapter 1. ISBN 92-5-104114-8.
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