Haemoglobin Flashcards
What are haemoglobin molecules
Quaternary protein make it easy to load oxygen in one condition and unload in another condition
How is the structure adapted for function
Primary structure is the sequence of amino acids
This then folds due to hydrogen bonding which Ford general 3D shape
Ionic bonds and disulphides bridges form in order to give haemoglovin its specific tertiary shape in order to carry oxygen
Then four polypeptide chain are combined and each polypeptide chain contains a ferrous ion which can carry an oxygen molecule
The role of haemoglobin
At gas exchange surface it need to bind readily with oxygen high affinity for oxygen called loading
In reassuring cells it needs to dissacociaye have low affinity for oxygen
How does haemoglobin l change affinity for oxygen
At alkaline conditions haemoglobin bonds readily to oxygen however in acidic conditions haemoglobin binds loosely to oxygen causing reay disassociation
Why do animals have different affinity for oxygen
The animals have different bases sequence as a result of different bases which result in different primary structure which causes the folding to be different which causes a different secondary structure which in turn creates a different tertiary specific shape so oxygen bonds to the molecule in a different way
Why is there an oxygen dissociation curve
Oxygen doesn’t bind equally to heamolglobin molecules when exposed to different partial pressures
How does positive cooperative work
When the first oxygen molecule bonds it very hard for oxygen to find a binding site as the protein is tightly coiled and has specific closed shape thus the graph is very shallow when the first oxygen bonds the quaternary shape of the molecule changes which makes it easier for consecutive oxygen molecules to bind so requires a smaller amount of increase in partial to pressure to allow oxygen to bind at the last oxygen molecule most of the binding sites are occupied so it’s hard for oxygen to find another binding site so the graph flattens out
Loading and unloading and transporting oxygen
In the lungs which is alkaline due to low level of co2 so the haemoglobin molecules changes shape so it has a high affinity for oxygen so readily bonds to the oxygen
It is transported in this shape to the cells as conditions are maintained
In the respiring cells the levels of co2 increases so the acidic conditions which change the shape of haemoglobin to bind readily to oxygen
