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Sweet Truth

Not All Carbohydrates Are Alike

Co Authors:

Ling Chen
Science Department
Borough of Manhattan Community College / City University of New York

Diane R. Wang
Biology, Plant Breeding and Genetics
Cornell University

Jennifer Y. Anderson
Health Science / Nursing
Brookdale Community College


This case reviews concepts of monosaccharide, disaccharide, and polysaccharide and contrasts the structures of different pairs of carbohydrates as well as the structure of sorbitol, a sugar substitute. It also depicts stereo chemistry concepts such as chiral carbon, enantiomer, anomer, Fisher projection, Haworth structure, and glycosidic bonds. In addition, the story associates the similar symptoms related to the gastrointestinal bacteria fermentation of lactose and soluble fibers and compares the enzymes that are responsible for the breakdown of lactose, amylose and cellulose. Furthermore, the case explains the health benefits of consuming insoluble fibers to prevent situations like constipation, diverticulosis, and colon cancer. Finally, the case study highlights the pros (for example, lowering absorptions of fats and glucose to prevent heart disease and the spike of the blood sugar levels after meals) and the cons (such as causing bloating and flatulence) of soluble-fiber consumption.

  • Use Fischer projection to identify the enantimoners of glucose (D- and L-glucose).
  • Define the structures of anomers of glucose.
  • Classify carbohydrates as monosaccharides, disaccharides, or polysaccharides.
  • Compare the disaccharide structures of maltose, lactose, and sucrose.
  • Contrast the structural difference of polysaccharides: cellulose and amylose.
  • Identify the common carbohydrates in food.
  • Identify the enzymes for digestion of lactose, amylose, and cellulose.
  • Explain the health benefits of consuming of soluble and insoluble fibers
Keywords: Carbohydrate; glucose; lactose; sucrose; amylase; cellulose; insoluble fiber; soluble fiber; fibre; monosaccharide; disaccharide; polysaccharide; glycosidic bond; enantiomer; anomer; sorbitol; sugar substitute; digestion; stereochemistry
Topical Area: N/A
Educational Level: Undergraduate lower division, Undergraduate upper division
Formats: PDF
Type/Method: Directed, Discussion
Language: English
Subject Headings: Chemistry (General)   Organic Chemistry   Biochemistry   Biology (General)   Food Science / Technology   Nutrition  
Date Posted: 5/11/2011
Date Modified: N/A
Copyright: Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

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