Biology 10.2 Oxygen Dissociation

Oxygen Dissociation Curves

When haemoglobin is exposed to different partial pressure of O = doesn't absorb oxygen evenly.

Low concs of O = 4 polypeptides of haemoglobin molecule = closely united = difficult to absorb first oxygen molecule.

Once loaded oxygen molecule causes polypeptides to load remaining 3 O moleculs very easily.

Graph of this relationship = oxygen dissociation curve.

V small decrease in partial pressure of O leads to lots of O becoming dissociated from haemoglobin.

V high concs of oxygen = graph tails off because haemoglobin is almost saturated with oxygen.

Shape of haemoglobin can change under different conditions = large number of different oxygen dissociation curves - roughly similar shape but position on axes differs:

• Further to the left the curve is = greater affinity of haemoglobin for oxygen (takes up more easily).
• Further to the right = lower affinity of haemoglobin for oxygen…