• Each amino acid contains an amine (-NH₂) and carboxylic acid (-COOH) group
• The -NH₂?group of?one amino acid?can react with the -COOH group of?another amino acid?in a?condensation reaction?to form a?dipeptide
  • The new?amide bond?between two amino acids is also called a?peptide link?or?peptide bond
• Since this is a condensation reaction, a small molecule (in this case H₂O) is?eliminated
• The?dipeptide?still contains an -NH₂?and -COOH group at each end of the molecule which can again participate in a condensation reaction to form a?tripeptide

A peptide bond is an amide bond between two amino acids

• A?polypeptide?is formed when?many?amino acids join together to form a long chain of molecules

A polypeptide is a long chain of amino acid molecules joined together