Amino Acids, Proteins & DNA

• Amino acids are the building blocks of proteins and are the basic units of amino acids. Amino acids can be separated and identified using TLC.
• Proteins are sequences of amino acids joined by peptide links
• Enzymes are proteins - active site binds to a substrate molecule and catalyses reactions
• A drug can act as an enzyme inhibitor by blocking the active site of an enzyme
• DNA exists as two complementary strands arranged in the form of a double helix
• What is an amino acid?


  A compound with an amine group and a carboxylic acid group within the molecule

  • The amine group is always on the second carbon in the chain, meaning they are named as '2-amino acids'
  • The second carbon is often chiral as it has 4 groups bonded meaning amino acids exist as optical isomers (however in nature all amino acids exist as a single negative enantiomer)
• Zwitterions


  The two functional groups within a single molecule means that amino acids can react as both acids and bases depending on reaction conditions

  In acidic conditions (low pH), the lone electron pair is more likely to accept a hydrogen atom, producing (acidic) end to the molecule