Behavioral Objectives

          Chapter 4

          Purdue griffin

          1. Define and/or identify:

          • DP
          • polydisperse
          • polymolecular
          • fringed micelle
          • syneresis
          • DS
          • MS
          • homoglycan
          • heteroglycan
          2. Describe and discuss the polydisperse and/or polymolecular nature of polysaccharides with respect to their purification, fractionation, homogeneity, and/or structural analysis.

          3. a. Use correctly the several official names for polysaccharides.

          b. Describe composition and structure based upon names, and vice versa. For example,

          • galactomannan
          • D-galactoD-mannan
          • poly(D-galactose-D-mannose)


          4.  Make interconversions between abbreviated names such as aLAraf(1,4)Xylp and Haworth and/or conformational structures for oligo- and polysaccharide structures containing D-glucose, D-galactose, D-mannose, D-glucuronic acid, D-galacturonic acid, D-mannuronic acid, L-guluronic acid, D-xylose, and/or L-arabinose.

          5. Outline the general steps in the determination of chemical structures of polysaccharides.

          6. Briefly describe the procedures to analyze the monomer composition, position of linkages, oligomers structure, and molecular weight of polysaccharide. A flow chart is preferred.

          7. Given methylation analysis and other data on an oligo- or polysaccharide, deduce the chemical structure of that oligo- or polysaccharide and discuss any limitations of the data with regard to a description of the complete chemical structure.

          8. Describe and discuss the relationship of polysaccharide structure to solubility, solution stability, and viscosity.

          9.  Give the molecular explanation for the differences in solution viscosity of linear and branch-on-branch polysaccharides of the same molecular weight (and concentration).

          10. Describe and discuss the stability of polysaccharides to heat, acid, and/or oxidizing agents.

          11. Discuss the factors involved in, and a general procedure for, making a gum solution.

          12. Describe depolymerization of polysaccharides via acid catalyzed hydrolysis, discussing the variables involved (acid concentration, temperature, time, structure [sugar type, linkages]).

          13. Describe depolymerization of polysaccharides in alkaline solution in the presence of air.

          14.  Given analytical information about a modified polysaccharide, calculate the DS or MS as appropriate; or given the DS, calculate the number of substituent groups per polysaccharide unit of given length.

          15.  Understand the definition of weight average molecular weight (Mw), number average molecular weight (Mn), and polydispersity.

          16.  When given the number and molecular weight of two or three groups of molecules, be able to calculate Mw, Mn, and polydispersity index (see slide 72 in Dr. Yao's starch lecture).

          17.  Describe three types of classification for polysaccharides. List two types of polysaccharide for each category of each type of classification.

          18.  Calculate the polydispersity index of the system containing following glucans:
          (1)    Group 1: 10 moles of DP 1000
          (2)    Group 2: 20 moles of DP 500
          (3)    Group 3: 50 moles of DP 100

          19.   Describe the functions of amino acid residues in the catalytic center of -amylase in the double displacement mechanism.

          20.  Schematically describe the formation of fish eyes during gum dispersion and list three approaches to prevent fish eyes formation. What can be done once fish eyes are formed?

          21.  Compared with other gums, why gum arabic is highly soluble in water without causing high viscosity?

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          Web Authors: James R. Daniel, Ph. D., Yuan Yao,  and James N. BeMiller, Ph. D.
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