- found in red blood cells
- large globular protein with a quaternaru structure
- each polypeptide chain has a haem group which contains iron
- high infinity for oxygen
- carries four oxygen molecules
- oxygen + haemoglobin = oxyhaemoglobin
Where the partial pressure is low it has a low affinity for oxygen.
the S shape is because the first O2 molecule to combine with haemoglobin makes it easier for the other molecules to join as its shape alters slightly.
- blood has a higher infinity for oxygen
- recieve oxygen from mothers blood across the placenta
- oxygen saturation decreases as it reaches fetus - therefor needs a higher affinity
- haemoglobin gives up its oxygen more readily when there's a higher partial pressure of CO2
- when cells respire they produce CO2
- the CO2 is converted into carbonic acid by the enzyme carbonic anhydrase
- carbonic acid splits up to form hydrogen irons and hydrogencarbonate irons
- the increase in hydrogen ions causes oxyhaemoglobin to unload its oxygen so it can take up the hydrogen ions. - to form haemoglobinic acid
- the hydrogencarbonate ions diffuse out the red blood cells and are transported in the blood plasma
- in the lungs the C02 ions reform CO2 then diffuse into alveoli and are breathed out.