Proteins (Cambridge O Level Chemistry)

• Proteins are condensation polymers which are formed from amino acid monomers joined together by amide links (in proteins also known as a peptide link) similar to the structure in nylon
• The units in proteins are different however, consisting of amino acids
• Amino acids are small molecules containing NH₂ and COOH functional groups

General structure of an amino acid 

• There are twenty common amino acids, each differing by their side chain, represented by R
• Proteins can contain between 60 and 600 of these amino acids in different orders 
• These are the monomers which polymerise to form the protein

 Diagram showing condensation polymerisation to produce a protein

• The structure of proteins can be represented using the following diagram whereby the boxes represent the carbon chains

Diagram showing a section of protein