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4 Cards in this Set

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Describe the structure of haemoglobin?

*Primary structure - 4 polypeptide chains.


*Secondary structure - Coiled into helix.


*Tertiary structure - Each polypeptide is folded into precise shape {to carry O2}.


*Quarternary structure - Polypeptide chains linked to form almost spherical molecule.


*Polypeptides each have Haem group & is a globular protein. Structure curled up so hydrophilic side chains face outwards & hydrophobic chains face inwards - Soluble - Good for transport in blood.

What types of haemoglobin are there?

*Haemoglobin with a high affinity for oxygen. These take up oxygen more easily but release less readily.



*Haemoglobin with a low affinity for oxygen. These take up oxygen less easily but release it more readily.

What is the role of haemoglobin & how much oxygen can a haem group hold?

*To transport oxygen, to do this it must:-


-> Readily associate with oxygen at the gas exchange surface.


-> Readily dissociate from oxygen at the tissue requiring it.



*1 oxygen molecule per haem group:-


Hb + 4O2 <-> Hb(O2)4

When does haemoglobin have a high affinity & a low affinity for oxygen?

*High affinity for oxygen at gas exchange surface so oxygen binds.



*Low affinity for oxygen at respiring tissues. High concentration of CO2 causes Hb to change shape, releasing oxygen.