Haemoglobin

• What type of molecule is haemoglobin

  Protein
• How many polypeptide chains make up hemoglobin?

  four (2 alpha and 2 beta)
• What does haemoglobin transport

  Oxygen
• What is the primary structure of haemoglobin


  The order of amino acids in the polypeptide chains
• What is the secondary structure of haemoglobin

  The coiling of the polypeptide chains into an alpha helix or beta pleated sheet via hydrogen bonds
• What is the tertiary structure of haemoglobin

  The folding of the polypeptide chains into a specific shape. Further hydrogen bonding, ionic bonds, disulphide bridges.
• What is the quaternary structure of haemoglobin

  The linking of the 4 polypeptide chains into an almost spherical molecule. Each polypeptide chain also has an associated haem group.
• What ion does a Haem group contain

  Fe2+
• How many oxygen molecules does each Fe2+ ion combine with

  1 oxygen per Fe2+
• How many oxygen molecules can a molecule of haemoglobin carry in humans

  4, one per Fe2+ ion in each haem group. 1 haem group in each polypeptide chain. 4 polypeptide chains.
• What is the name to the process which haemoglobin binds with oxygen

  Loading or associating
• What is the name to the process by which haemoglobin releases oxygen

  Unloading or dissociating
• What does affinity mean with respect to haemoglobin


  Affinity is the relative attraction of haemoglobin to oxygen.
• If haemoglobin has high affinity, what does this mean?

  Easier to load oxygen, harder to unload oxygen
• If haemoglobin has a low affinity, what does this mean?

  Harder to load oxygen, easier to unload oxygen
• To be good at transporting oxygen, what 2 characteristics must haemoglobin have?

  It must readily associate with oxygen where gas exchange occurs. It must readily dissociate when from oxygen in tissues which require it.
• How does haemoglobin change its affinity for oxygen

  It will change shape when in the presence of certain molecules (e.g. carbon dioxide). If present, the carbon dioxide changes the shape, so the oxygen no longer fits as well, and is easily disassociated.
• What is the name given to the increase in ease of binding for 2nd, 3rd and 4th oxygen molecules

  positive cooperativity
• Where in the body does haemoglobin have a high affinity for oxygen

  lungs
• Where in the body does haemoglobin have a low affinity for oxygen

  Body cells