Dissociation

• Haemoglobin has a quaternary structure that is able to transport oxygen
• curve represents relationship between partial pressure of oxygen and percentage saturation of haemoglobin with oxygen
• when partial pressure of oxygen is high, oxygen association takes place and haemoglobin has a higher affinity for oxygen here.
• when partial pressure is low like at respiring tissue oxygen dissociaton takes place and so haemoglobin has a lower affinity for oxygen here
• steep gradient in curve is a result of positive cooperativity
• when an oxygen molecule binds to haemoglobin. haemoglobin quaternary structure changes to uncover other iron atoms. Making it easier for other oxygen molecules to bind
• when one oxygen molecule unbinds the quaternary structure changes to make it easier for others to unbind by covering the iron atom
• The effect of co2 on the oxyhaemoglobin dissociation curve is known as the bohr affect.#
• At low concentration of co2 haemoglobin has a high affinity for oxygen. It associates more readily with oxygen
• At high concentrations of co2. Haemoglobin has a lower affinity for oxygen and dissociates more readily. This is because co2 conc affects blood ph. As co2 conc increases the concertation of h+ ions increases so the ph decreases
• Due to the ph decreasing this causes the shape of haemoglobin to change such as that it is easier for oxygen to dissociate and when co2 decreases the ph increases changing the shape so easier for oxygen to associate