proteins

• amino acids -

  monomers from which proteins are made
• general structure of amino acid -

  COOH - carboxyll group, NH3 - amine group, R- side chain
• how do amino acids differ?

  in their side groups
• bonds formed -

  peptide bond
• functional protein -

  may contain one or more polypeptides
• H bonds - 


  easily broken
• ionic bonds -

  between the carboxyll and amine group, fairly easily broken
• disulphide bridges -

  between r group and cytosine, very strong
• primary structure -

  order of amino acids
• secondary structure -

  shape of chain, a helix or b pleated sheet
• tertiary structure -

  3d shape with bonds
• quarternary structure -

  arrangement of polypeptide chains
• biuret test -

  1.sample in test tube

  2.add equal amount of odium hydroxide

  3.add a few drops of copper sulphate and mix gently

  4.purple colour shows peptide bond and a protein

  negative remains blue