Haemoglobin

• What is the role of haemoglobin?

  Carry oxygen around the body
• Where is haemoglobin found?

  Red blood cells
• Where can haemoglobin be found?

  All vertebras, earthworms, starfish, some insects, some plants and some bacteria.
• What is the structure of haemoglobin?

  Large protein with a quaternary structure, made up of four polypeptide chains.

  Each chain has a haem group which contains an iron ion and gives haemoglobin it's red colour.

  Each molecule of human haemoglobin can carry four oxygen molecules
• When an oxygen joins to a haemoglobin

  Association or loading
• When an oxygen leaves oxyhaemoglobin

  Dissociation or unloading
• What does affinity for oxygen mean?

  The tendency which a molecule has to bind with oxygen
• What is partial pressure of oxygen? (pO2)

  measure of oxygen concentration - one of the conditions which affect affinity.
• How does partial pressure of oxygen affect affinity?

  The greater the partial pressure, the higher haemoglobins affinity is.
• What are the conditions for oxygen to load and unload?

  Loads onto haemoglobin to form oxyhaemoglobin where there is a high pO2.

  Oxyhaemoglobin unloads its oxygen when there is a lower pO2.
• How does haemoglobin load and unload in the lungs?

  1. Oxygen enters the blood capillaries at the alveoli in the lungs
  2. Alveoli has a high pO2, so oxygen loads onto the haemoglobin
  3. Cells respire, they use up oxygen - so this is lowering the pO2.
  4. Red blood cells deliver the oxyhaemoglobin to the respiring tissue and then it unloads its oxygen.
  5. The haemoglobin returns to the lungs to pick up more oxygen
• What does it mean when the saturation of oxygen is high?

  The pO2 is high, so the haemoglobin has a higher affinity
• What does it mean when the saturation of oxygen is low?

  The pO2 is low, therefore haemoglobin has a lower affinity for oxygen
• What is the partial pressure of carbon dioxide? (pCO2)

  Measure of concentration of CO2 in a cell - affects oxygens unloading
• How does pCO2 affect unloading?

  Haemoglobin gives up its oxygen more readily at a higher pCO2
• What is the Bohr effect?

  Cells produce carbon dioxide when they respire, therefore increasing the rate of oxygen unloading. The dissociation curve then shifts to the right and the saturation of blood with oxygen will be lower, therefore more oxygen is being released.
• What type of haemoglobin do low oxygen environments have?

  Haemoglobin with a higher affinity for oxygen because there is little oxygen available, therefore it has to be good at loading for any available oxygen.
• Where is the dissociation curve for low oxygen environments?

  Further to the left compared to a human
• What type of haemoglobin do high activity levels have?

  Haemoglobin with a lower affinity because they are more active and have a higher oxygen demand - the oxygen needs to be able to easily unload so its available to use when needed.
• Where is the dissociation curve for high activity levels?

  Further to the right compared to a human
• What type of haemoglobin do smaller organisms have?

  Lower affinity for oxygen because they have a higher demand for oxygen due to having a high metabolic rate - they have a higher surface area to volume ratio so they lose heat quicker.
• Where is the dissociation curve for smaller organisms?

  Further to the right compared to a human