Navigation Links

Polysaccharides (sometimes called glycans) are relatively complex carbohydrates.

They are polymers made up of many monosaccharides joined together by glycosidic linkages. They are therefore very large, often branched, molecules. They tend to be amorphous, insolubile in water, and have no sweet taste.

When all the constituent monosaccharides are of the same type they are termed homopolysaccharides; when more than one type of monosaccharide is present they are termed heteropolysaccharides.

Examples include storage polysaccharides such as starch and glycogen and structural polysaccharides such as cellulose.



Starches are polymers of glucose in which glucopyranose units are bonded by alpha-linkages. Amylose consists of a linear chain of several hundred glucose molecules. Amylopectine is a branched molecule made of several thousand of glucose units.
Starches are insoluble in water. They can be digested by hydrolysis catalyzed by enzymes called amylases, which can break the alpha-linkages. Humans and other animals have amylases, so they can digest starches. Potato, rice, wheat, and maize are major sources of starch in the human diet.


Glycogen is the storage form of glucose in animals. It is a branched polymer of glucose. Glycogen can be broken down to form substrates for respiration, through the process of glycogenolysis. This involves the breaking of most of the C-O-C bonds between the glucose molecules by the addition of a phosphate, rather than a water as in hydrolysis. This process yields phosphorylated glucose molecules, which can be metabolized with a savings of one ATP molecule.


The structural components of plants are formed primarily from cellulose. Wood is largely cellulose and lignin, while paper and cotton are nearly pure cellulose. Cellulose is a polymer made with repeated glucose units bonded together by beta-linkages. Humans and many other animals lack an enzyme to break the beta-linkages, so they do not digest cellulose. Certain animals can digest cellulose, because bacteria possesing the enzyme are present in their gut.

Acidic polysaccharides

Acidic polysaccharides are a group of polysaccharides that contain carboxyl groups and/or sulfuric ester groups .


(Date:8/31/2014)... the greatest challenges in modern medicine is developing drugs ... minimal toxicity and side-effects to the patient. Such properties ... drug molecule. Ideally, the drug should have a shape ... that it binds it with high specificity. Publishing in ... synthetic amino acid that can impact the 3D structure ...
(Date:8/31/2014)... malaria diagnosis has changed very little. After taking a blood ... a glass slide, stains it with a special dye, and ... the disease. This approach gives an accurate count of how ... of disease severity but is not ideal because there ... the Singapore-MIT Alliance for Research and Technology (SMART) has now ...
(Date:8/29/2014)... recently, little has been known about what genetic changes ... of scientists, one of whom is a University of ... that genes controlling the development of the brain and ... The study was published Aug. 28 in Science ... is online at ., The domestication of ...
Breaking Biology News(10 mins):A new synthetic amino acid for an emerging class of drugs 2A new synthetic amino acid for an emerging class of drugs 3A new way to diagnose malaria 2A new way to diagnose malaria 3New research reveals how wild rabbits were genetically transformed into tame rabbits 2New research reveals how wild rabbits were genetically transformed into tame rabbits 3
... CAMBRIDGE, Mass. (March 16, 2011) Renowned cancer researchers ... Douglas Hanahan, Director of the Swiss Institute for Experimental ... "Hallmarks of Cancer," which has influenced the study of ... a decade. Published in January 2000, their original ...
... Global Change Biology Bioenergy proposes a new method ... in bioenergy systems. CO 2 emissions resulting from ... and environmental impact studies because bioenergy is carbon- and climate- ... combustion are sequestered by growing biomass. Its climate impact has ...
... Mass., March 16, 2011 The nutritional content of ... as owner,s perceptions about them, according to a study ... School of Veterinary Medicine at Tufts University. ... humans and petschange with aging, the Association of American ...
Cached Biology News:Whitehead scientist helps revisit 'Hallmarks of Cancer' 2Whitehead scientist helps revisit 'Hallmarks of Cancer' 3Wide variety in nutritional content found in 'senior' dog foods 2Wide variety in nutritional content found in 'senior' dog foods 3
Other biology definitionOther Tags