proteins

• structure of amino acids:

  
• proteins:

  polymers made up of monomers - amino acids
• how is the bond between dipeptides/polypeptides formed?

  through a condensation reaction - forming peptide bonds at the OH in carboxyl and H in amino group
• primary structure of proteins

  order of sequence of amino acids joined by peptide bonds
• secondary structure of proteins

  primary structure coiled to make alpha helix / beta pleated sheets

  • held by hydrogen bonds
• tertiary structure of proteins

  folding of secondary structure:

  • has a unique 3D shape
  • consists of: ionic bonds & hydrogen bonds & disulfide bridges
  • between R groups
• quaternary structure of proteins

  more than 1 polypeptide chain joined together

  eg: haemoglobin - has 4 polypeptide chains
• test for proteins:

  add sodium hydroxide - makes solution alkaline

  add biurets reagent and shake

  positive result: blue--> purple