CHEM 102 Chapter 10 Lecture 18 Outline of Last Lecture I. Stereoisomers VS. Constitutional isomersII. Two Types of StereoisomersIII. Tetrahedral Stereocenter (Chiral)IV. Carbohydrates and their FunctionsV. Class of Carbohydratesa. MonosaccharidesVI. D and L DiastereomersVII. Cyclic Structurea. Hemiacetal CarbonOutline of Current LectureII. Chemical and Physical Properties of MonosaccharidesII. Disaccharides a. Glycosidic Bondb. Important DisaccharidesIII. Reducing SugarsIV. PolysaccharidesCurrent LectureChemical and Physical Properties of Monosaccharides1. Due to strong hydrogen bonding, monosaccharides are solids at room temperature and are very soluble in water2. Most Monosaccharides are sweet to the taste, some more than others. Fructose is the sweetest of all MonosaccharidesDisaccharidesDisaccharide- two monosaccharides connected together by a glycosidic bondThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Glycosidic Bond- the two monosaccharides are bonded together by an Oxygen molecule Ex. http://science.uvu.edu/ochem/wp-content/images/G/glycosidiclink1.pngNaming Linkage for Disaccharides- To name the linkage as Alpha or Beta, you will look at the Hemiacetal Carbon that has the Glycosidic Oxygen bond on it. Compare the Glycosidic Oxygen to the 6th carbon’s OH group and decide if it is Alpha or Beta.- To find out the Linkage, simply look at which carbons the Glycosidic Bond was formed to (Usually a 14 Linkage bond but not always) Ex. This is an example of the linkage name for a Disaccharide αD-MaltoseNaming Disaccharides in general- Find the Hemiacetal Carbon on the second monosaccharide in the disaccharide. Compare the OH group from the Hemiacetal Carbons to the OH group on the 6th carbon. Name if it is Alpha or Beta Ex. βD-CellobioseImportant Disaccharides1. Maltose- (malt sugar) produced by the partial hydrolysis of starch by the enzyme amylase which is secreted into the mouth by the salivary glands and the small intestine by the pancreas: Made from two D-Glucose residues linked by an α(1  4) glycosidic Linkage2. Cellobiose- produced by the partial hydrolysis of cellulose by the enzyme cellulase; madefrom two D-Glucose residues like by a β(1 4) glycosidic Linkage3. Lactose-(milk sugar) constitutes 4-8% of mammalian milk and is the major energy sourcefor infants; contains D-Galactose and D-Glucose residue connected by β(14) glycosidic linkage4. Sucrose-(cane sugar) most abundant disaccharide in nature, found in fruits and vegetables: made from a D-Glucose and a D-Fructose residue and connected by an5. αβααα,β(1α,β(12) glycosidic linkage EX. http://2012books.lardbucket.org/books/introduction-to-chemistry-general-organic-and-biological/section_19/760d20a66330a0aba1a196431f7bc177.jpgReducing Sugars- Mild Oxidation agents such as Benedict’s Reagent can oxidize the C1 Carbon forming a carboxylic acid and prodicing a red precipitate of Cu2O- Disaccharides that give a positive test must have one hemiacetal carbon- Maltose, Cellobiose, and Lactose are reducing sugars- Sucrose is not due to no hemiacetal carbon, and would give a negative Benedict’s test resultPolysaccharidesPolysaccharides- polymers containing a large number of monosaccharides; They usually differ structurally in several ways- The –OH groups participate in glycosidic bonds- Can have branching chainsStarch- storage/nutritional polysaccharide where D-Glucose is stored in plantsGlycogen- storage/nutritional polysaccharide where D-Glucose is stored in animals- Starch is found in plant cells as two different polyglucose molecules, Amylose and AmylopectinAmylose- Linear polymer of D-Glucose bonded by a α(14) glycosidic linkageEx. http://www.smartkitchen.com/assets/images/resources/large/1329761636amylose.jpgAmylopectin- Has a branching chain with an α(16) glycosidic linkage Ex. http://www.smartkitchen.com/assets/images/resources/large/1329761849amylopectin.jpgCellulose- Linear polymer of D-Glucose; β(14) glycosidic linkage Ex. http://chemistry2.csudh.edu/rpendarvis/cellulose.GIFPolysaccharides are NOT reducing sugars, even though they have hemiacetal