Carbohydrates Learning goal Students should be able to apply chemical principles to understanding the properties of the second category of biological molecules the carbohydrates They should be familiar with general principles of carbohydrate polymerization structure and function Focus Monomers Polymerization Diverse functions beyond mere energy 2 Part 1 monomers Monomers monosaccharides carbohydrate refers to the base ratio of C H and O in most sugars CH2O n monomers have at least one C O bond and multiple C OH and C H bonds these are generally the only functional groups present 3 Monosaccharide carbons are assigned numbers for describing bonds C3H6O3 Glucose C6H12O6 Fructose C6H12O6 4 Monomers have two forms Linear and ring forms in equilibrium glucose glucose Glucose C6H12O6 5 Most common monosaccharides have six carbons and form 5 or 6sided rings Ribose is part of nucleic acid structure and has five carbons Figure 4 1 7 Part 2 polymerization Polymerization of monomers into chains For many of the large polysaccharides the monomer is glucose Complex carbohydrates do not have the CH2O n formula any longer why not 8 Polymerization Reaction polysaccharide version 9 Depolymerization Reaction polysaccharide version 10 Part 2 polymerization Similarities to other proteins 1 2 Dehydration hydrolysis reactions predominantly linear primary structure Differences 1 Glycosidic bonds 2 Geometry of bonds can vary 3 Polymers not always linear 11 Carbohydrate polymers fall into three categories Disaccharides 2 Oligosaccharides less than 50 Polysaccharides can go on for hundreds of monomers In this class I only ask that you know the primary and secondary structures of the most common polysaccharides where 1 Glucose is the only monomer 2 There are only three glycosidic link configurations 13 Book figure 5 4 shows formation of lactose disaccharide from galactose and glucose Next slide shows formation of 1 4 linkage between two glucose molecules Figure 5 4 14 glucose chain joined by 1 4 glycosidic links glucose chain joined by 1 4 glycosidic links 15 Part 3 functions of carbohydrates ALL serve as potential sources of energy The more C H and C C bonds a molecule has the higher the amount of energy it contains 16 Functions energy storage summary table 5 1 17 Functions energy storage summary table 5 1 18 Pause to compare Comparisons to protein primary structure helices Comparisons to protein secondary structure Enzymes only create one kind of bond Part 3 functions of carbohydrates ALL serve as for other organic molecules including proteins lipids and nucleic acids and any other category of macromolecule can be converted into a carbohydrate 21 Functions structural support summary table 5 1 22 Pause to compare Similarities between cellulose secondary structure and protein secondary structure Oligosaccharides can be attached to proteins lipids or can bridge the two to create a hybrid molecule glycoprotein glycolipid Glycophosphatidylinositol GPI anchored protein Oligosaccharides function in cell recognition and signaling Oligo a few monomers diverse not limited to glucose not limited to hexoses linkages also diverse 25 Multiple enzymes are required for oligosaccharide synthesis Oligosaccharides form the ABO blood groups 26 Oligosaccharide shipping labels are added to proteins in ER Oligosaccharires are created in the rough ER by figure 7 19 27 For the exam midterm 2 You should be able to describe the structure and function of carbohydrate monomers and polymers in a general sense in biological systems including why types of glycosidic linkages matter You should be able to relate what you learned in chapter two to discuss the properties of mono and polysaccharides in water based on the functional groups you can identify re solubility hydrophobic hydrophilic etc You should be able to compare and contrast how polysaccharides are similar and different from the other categories of biological molecules You should come back to these slides when we discuss The ER signaling pathway unit 3 Cell cell communication and signaling unit 4 28