oxygen association/dissociation

• Red blood cell


  Contains hemoglobin to transport oxygen in the blood
• Hemoglobin


  A quaternary structure protein with 4 polypeptide chains, each containing a heme group with iron that binds oxygen
• There are different types of hemoglobin found in different organisms and tissues</b>
• Affinity


  The ability of hemoglobin to attract and bind oxygen
• Saturation


  The maximum amount of oxygen that hemoglobin can bind
• Loading/Association


  When oxygen is binding to hemoglobin
• Unloading/Dissociation


  When oxygen is detaching or unbinding from hemoglobin
• Oxyhemoglobin dissociation curve


  • Sigmoid (S-shaped) curve
  • Demonstrates how hemoglobin's affinity for oxygen changes at different partial pressures of oxygen
• High partial pressure of oxygen

  Hemoglobin is almost 100% saturated with oxygen
• Low partial pressure of oxygen

  Hemoglobin is only about 50% saturated with oxygen
• Cooperative binding


  The first oxygens bind with difficulty, but then subsequent oxygens bind much more easily due to a change in hemoglobin's shape
• Bohr effect


  The decrease in hemoglobin's affinity for oxygen when there is a high concentration of carbon dioxide, which makes the blood more acidic
• High carbon dioxide concentration

  Oxyhemoglobin dissociation curve shifts to the right, indicating lower affinity for oxygen
• Low carbon dioxide concentration

  Oxyhemoglobin dissociation curve shifts to the left, indicating higher affinity for oxygen
• Fetal hemoglobin


  • Has a higher affinity for oxygen compared to adult hemoglobin, allowing the fetus to obtain oxygen from the mother's blood
• Llama hemoglobin


  • Has a higher affinity for oxygen compared to human hemoglobin, allowing llamas to function at high altitudes with low oxygen levels
• Dove hemoglobin


  • Has a lower affinity for oxygen compared to human hemoglobin, allowing doves to readily unload oxygen to their high-metabolism muscles during flight
• Earthworm hemoglobin


  • Has a higher affinity for oxygen compared to human hemoglobin, allowing earthworms to obtain sufficient oxygen even in their low-oxygen underground environment
• Each hemoglobin tetramer can carry four oxygen molecules.
• The binding of oxygen to hemoglobin increases its affinity for more oxygen molecules.
• The binding sites on hemoglobin are called heme groups or hemes.
• When one oxygen molecule is bound to a heme group, it changes the shape of the protein slightly, making it easier for another oxygen molecule to bind.