Essential Elements of Biochemistry BCHM 3050 Dr Srikripa Chandrasekaran Lecture 4 1 15 Notes Carbohydrates I Isomers same number of carbon atoms just different arrangement Monosaccharides A The 2 main classifications of sugars are aldose and ketose B Most sugars have isomer forms C D Many isomers are non superimposable mirror images E Enantiomers non superimposable mirror image isomers F Diastereomers isomers that are not mirror images G Stereoisomers 1 Enantiomers 2 Diastereomers Epimers H Glucose and galactose differ around carbon atom 4 I Glucose and mannose differ around carbon atom 2 J An alpha glucose is when the O points away from the OH on C 1 when the O and OH are on different planes K A beta glucose is when the O points towards the OH on C 1 when the O and OH are on the same plane L Know the structures of all of these sugars M Epimer examples 1 Glucose vs Mannose C 2 2 Glucose vs Galactose C 4 3 Alpha Glucose vs Beta Glucose C 1 This is also an example of an anomer II Chemical reactions of monosaccharides A The aldehyde group or the CH2OH group can get oxidized and depending on which one does get oxidized changes the name B Oxidation is very important because these acids go on to make other products C When gluconic acid cyclizes one of the products is Vitamin C D Vitamin C is formed by the cyclization of glucose E Sorbitol is a stress inducer F When the aldehyde group gets used you get CH2OH G When CH2OH gets oxidized you get an aldyhyde H When glucose has 2 CH2OH groups it is called glucitol Examples of monosaccharides A The difference between glucose and galactose the OH on C 4 of galactose is pointing up while the OH on C 4 of glucose is pointing down B Fructose is a pentamer 5 membered ring III 1 C The body is supposed to be able to make galactose and if it cannot the person has a genetic disorder IV Disaccharides A Disaccharides When 2 sugars interact with each other and become connected via a glycosidic bond B Most disaccharides the first sugar contributes C 1 which interacts C Most lactose found in nature consists of beta glucose and beta or with C 4 of the second sugar alpha galactose D Beta 1 4 the 1 refers to the glucose and the 4 refers to the E F galactose If beta glucose and beta galactose are bonded together it is called beta lactose and the bond is beta 1 4 If beta glucose and alpha galactose are bonded together it is called alpha lactose but the bond is still beta 1 4 G Lactose is a reducing sugar which means it has a free carbon if a sugar has a free carbon that means It can interact with another sugar and form a bond H This linkage in maltose is called alpha 1 4 because the OH is pointing down I The form of maltose found is nature is alpha alpha J Beta glucose and beta glucose bond together to form cellobiose 1 The linkage is called beta 1 4 K Sucrose is the only bond that has a bond called alpha beta L Sucrose cannot increase its size 2
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