Biology 10.2 Oxygen Dissociation

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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…

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