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By the end of this lesson, you will be able to:

  1. define, describe and give at least 2 examples of a typical monosaccharide and be able to identify one from its structural (ring only) and/or molecular formula.
  2. state the general functions of monosaccharides in living systems and their roles in cellular biochemistry.
  3. identify the linkage between monosaccharides as a glycosidic linkage (a specific type of ether) and identify where 1→>4  and 1→6 linkages form.
  4. explain the forms of glucose in terms of structure, properties, formation, type of isomer.
  5. describe the structure of a typical disaccharide, be able to identify one from its structural and/or molecular formula and give at least 2 examples.
  6. describe the structure of a typical polysaccharide and be able to identify one from its structural formula, and be able to explain the impact of both the carbon linkages (1→4, 1→6) and type of linkages (alpha or ß) on the molecular characteristics.
  7. state the general functions of polysaccharides (starch, glycogen, cellulose, chitin) in living systems.

Sugars and starches form and group of organic compounds known as the carbohydrates.  These biologically important molecules are the primary energy source for living organisms.  

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Carbohydrates are the main source of energy for cells; mitochondria convert glucose to the metabolically useable ATP. Carbohydrates consist of C, H and O in a 1:2:1 ratio. The monosaccharides (monomers) are named by the number of carbons they contain; they can exist in different isomeric forms, e.g. structural, geometric,enantiomer. DIsaccharides are formed by condensation reactions between 2 monosaccharides; their biophysical properties are determined by the type of isometric linkage. Polysaccharides such as starch and glycogen are storage forms of glucose for plants and animals respectively, while cellulose makes up plant cell walls.

Source: M. O'Mahony, open source figures


Carbohydrates are the main source of metabolic energy for the cell; glucose is used by the mitochondria to generate ATP. They can exist as monosaccharides which show examples of structural, geometric and enantiomer isomers. Disaccharides are a result of glycosidic linkages between two monosaccharides. The polysaccharides are primarily polymers of glucose and used for storage of glucose (starch and glycogen) and structure (cellulose).

Source: M. O'Mahony, open source figures


This is the student note template for this lecture


Source: M. O'Mahony, open source figures

Molecular Workbench

Go to the site:

and select Lipids and Carbs.

The Majority of this page is about carbohydrates.

This simulator requires Java.

Source: Molecular Workbench, The Concord Consortium