Protein Structure and Levels

• What does the "Biuret Test" test for?


  Peptide Bonds
• What is the Primary Structure of a Protein?


  The Sequence of Amino Acids in a Polypeptide Chain
• What is the Secondary Structure of a Protein?


  • The formation of Secondary Structures, primarily Alpha-Helices and Beta-Pleated sheet
  • Secondary structures from as a result of hydrogen bonding between Amino Acids in the chain
• Where can Hydrogen Bonds form in the secondary structure?


  Between:

  • The Carboxyl Group of one Amino Acid and the Amine Group of another
  • The Carboxyl Group of one Amino Acid and the Hydroxyl Group of another
• What is the Tertiary Structure of a Protein?


  • A complex 3D shape formed when a Helix or Sheet twists and folds around itself
  • Held together by many different bonds such as Hydrogen, Ionic, Disulphide and Van Der Waal’s forces
• How can Hydrogen Bonds be broken?


  High Temperatures and Altered pH
• How can an Ionic Bond be broken?


  Change in pH
• How can Disulphide bonds be broken?


  With Reducing Agents
• What are Globular Proteins?


  A spherical mass that folds in a way so that Hydrophilic molecules are on the outside, and Hydrophobic molecules are on the inside
• What is the Quaternary Structure of a Protein?


  The linking of a number of polypeptide chains
• What is an example of a protein with a Quaternary Structure?


  Haemoglobin
• What can Quaternary Structures have that others can’t?


  Non-amino acid groups called Prosthetic Groups
• Globular Proteins tend to be…?


  Soluble
• Fibrous Proteins tend to be…?


  Insoluble and Strong so they have a structural role
• Why do Enzymes have a Globular Structure?


  To form their respective active sites