Biological Molecules

Introduction to Biological Molecules


  • Covalent
  • Ionic 
  • Hydrogen


Monomers can be linked together to form long chains. Long chains of monomer sub-units are called polymers and the process is polymerisation.

Condensation and Hydrolysis Reactions

In the formation of polymers by polymerisation, each time a new sub-unit is added a molecule of water is formed. This is a condensation reaction. 

Polymers can be broken by addition of water, breaking bonds linking sub-units of a polymer. This is a hydolysis reaction.


All the chemical processes that take place in the living organisms are collectively called metabolism.

Carbohydrates- Monosaccharides

Making large molecules

Examples of monomers include monosaccharides, amino acids, snd nucleotides. Monomers join together to form lomg chains polymers.


Sweet-tasting, soluble substances with general formula (CH2O)n. Examples of monosaccharides include glucose, galactose and fructose.

Test for reducing sugars

All monosaccharides and some disaccharides are reducing sugars. A reducing sugar can donate electrons to another chemical, in this case Benedicts Reagent. 

Benedicts test: Alkaline solution of copper (II) sulphate. When a reducing sugar is heated with Benedicts reagent it forms an insoluble red


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