Difference Between Homopolysaccharides and Heteropolysaccharides

Main Difference – Homopolysaccharides vs Heteropolysaccharides

Homopolysaccharides and heteropolysaccharides are polymer components. These polysaccharides are made out of monomers known as monosaccharides. Homopolysaccharides and heteropolysaccharides can be found as structural components in plant tissues and animal tissues. There are many commercially important polysaccharides as well. The main difference between homopolysaccharides and heteropolysaccharides is that homopolysaccharides are composed of the same repeating unit whereas heteropolysaccharides are composed of different repeating units.

Key Areas Covered

1. What are Homopolysaccharides
      – Definition, Chemical Bonding, Examples
2. What are Heteropolysaccharides
      – Definition, Examples
3. What is the Difference Between Homopolysaccharides and Heteropolysaccharides
      – Comparison of Key Differences

Key Term: Cellulose, Glucose, Glycosidic Bond, Heteropolysaccharide, Homopolysaccharide, Hyaluronic Acid, Monomers, Monosaccharides, Polysaccharides, Starch

What are Homopolysaccharides

Homopolysaccharides are chemical compounds that are composed of a single type of monomer. These monomers are monosaccharides. Therefore, the chemical structure of a homopolysaccharide has the same repeating unit.

A polysaccharide is made out of monomers that are covalently bonded to each other via glycosidic bonds. There can be two types of glycosidic bonds as 1-4 glycosidic bonds and 1-6 glycosidic bonds, depending on the carbon atoms that are bonded to each other (via an oxygen atom). The 1-4 glycosidic bonds cause the formation of a linear homopolysaccharide whereas 1-6 glycosidic bonds result in branched structures.

Figure 1: Bonding in Homopolysaccharides

Cellulose is a good example for homopolysaccharides. It is a linear homopolysaccharide with 1-4 glycosidic bonds. The monomer of cellulose is glucose. Glucose is a monosaccharide. Starch is another homopolysaccharide. It has two main components: amylose and amylopectin. Amylose is a linear structure whereas amylopectin is a branched structure. Cellulose and starch can be found in plants. There are homopolysaccharides in animal bodies as well. For example, glycogen is a homopolysaccharide of glucose monomers. Chitin is another homopolysaccharide which has N-acetylglucosamine as the monomer. It is the main structural component of insects.

What are Heteropolysaccharides

Heteropolysaccharides are polysaccharides that are made out of two or more different monosaccharides. These are polymers of monosaccharides. The polymeric structure of the heteropolysaccharide has different repeating units.  

Heteropolysaccharides are complex structures. The arrangement of repeating units decides the chemical and physical properties of the heteropolysaccharide. There are many well-known heteropolysaccharides. These compounds have various applications in biological systems and in industries as well.

Figure 2: Heteropolysaccharide

For example, Hyaluronic acid is a structural component that can only be found in animal tissues. It is a heteropolysaccharide of D-glucuronic acid and N-acetyl-D-glucosamine. Pectin can be found in plant tissues. It is also a heteropolysaccharide. This compound is made out of a D-galacturonic acid backbone that is bonded to different side chains.

Difference Between Homopolysaccharides and Heteropolysaccharides

Definition

Homopolysaccharides: Homopolysaccharides are chemical compounds that are composed of a single type of monomer.

Heteropolysaccharides: Heteropolysaccharides are polysaccharides that are made out of two or more different monosaccharides.

Repeating Units

Homopolysaccharides: Homopolysaccharides are composed of the same repeating unit.

Heteropolysaccharides: Heteropolysaccharides are composed of different repeating units.

Monosaccharides

Homopolysaccharides: Single type of monosaccharide is involved in the formation of a homopolysaccharide.

Heteropolysaccharides: Different types of monosaccharides are involved in the formation of a heteropolysaccharide.

Chemical Structure

Homopolysaccharides: Homopolysaccharides have simple structures when compared to heteropolysaccharides.

Heteropolysaccharides: Heteropolysaccharides have complex structures.

Conclusion

Polysaccharides are polymers that are made out of monosaccharides. The monosaccharides are linked to each other via glycosidic bonds. Depending on the type of monosaccharides involved in the formation of a polysaccharide, they can be divided into two major groups as homopolysaccharides and heteropolysaccharides.  The main difference between homopolysaccharides and heteropolysaccharides is that homopolysaccharides are composed of the same repeating unit whereas heteropolysaccharides are composed of different repeating units.

Reference:

1. “Homopolysacch” By jphwang.The original uploader was Jphwang at English Wikibooks – Own work (Public Domain) via Commons Wikimedia 
2. “Heteropolysaccharide” By Ccostell – Own work (Public Domain) via Commons Wikimedia