Haemoglobin Flashcards
(29 cards)
What is haemoglobin?
A protein with a quaternary structure.
Where does oxygen bind to on haemoglobin?
On the haem group which has iron within it.
What is the affinity of haemoglobin for oxygen?
The ability of haemoglobin to attract or bind to oxygen.
What is the saturation of haemoglobin with oxygen?
When haemoglobin is holding the maximum amount of oxygen it can bind.
What is loading/association of haemoglobin?
The binding of oxygen to haemoglobin.
Where does loading/association occur?
In the lungs
What is the unloading/dissociation of haemoglobin?
When oxygen detaches or unbinds from haemoglobin.
Where does unloading/dissociation occur?
In respiring tissues.
Where does oxygen have a high partial pressure?
Alveoli
Where is oxygen unloaded?
In regions of low partial pressure of oxygen e.g. respiring tissues.
What is the co-operative nature of oxygen binding to haemoglobin?
The haemoglobin changes shape when the first oxygen binds. This then makes it easier for the further oxygen molecules to bind.
What is the Bohr effect?
When a high concentration of carbon dioxide causes the oxyhaemoglobin curve to shift to the right. The affinity for oxygen decreases because the acidic carbon dioxide changes the shape of the haemoglobin slightly.
Do animals have the same haemoglobin? Why?
No because they have different affinities for oxygen which is an adaptation to their environment.
Describe the primary protein structure of haemoglobin.
The sequence of amino acids in the four polypeptide chains.
Describe the secondary protein structure of haemoglobin.
Each of the polypeptide chains are coiled into a helix.
Describe the tertiary protein structure of haemoglobin.
Each polypeptide chain is further folded into a precise shape whch is an important factor in its ability to carry oxygen.
What is the quaternary protein structure of haemoglobin?
All four polypeptides are linked together to form a spherical molecule. Each polypeptide is associated with a haem group which contains a ferrous ion. Each ferrous ion can combine with an oxygen molecule making a total of 4 oxygen molecules that can be carried out by a single haemoglobin molecule in humans.
What happens to a haemoglobin with a high affinity for oxygen?
They take up oxygen more easily but release it less easily. (Opposite for low affinity)
What is the role of haemoglobin?
To transport oxygen.
Describe the structure of haemoglobin.
Quaternary structure protein. Made up of four polypeptide chains. Each chain contains a haem group containing an iron ion.
Describe the role of red blood cells and haemoglobin in oxygen transport.
Red blood cells contain lots of haemoglobin - no nucleus, biconcave, high SA:V and short diffusion path.
Haemoglobin associates with oxygen at gas exchange surfaces where partial pressure of oxygen is high.
This forms oxyhaemoglobin which transports oxygen. Haemoglobin dissociates from oxygen near tissues where partial pressure of oxygen is low.
Describe the loading, transport and unloading of oxygen in areas with low partial pressure of oxygen. (In relation to the oxyhaemoglobin dissociation curve)
Haemoglobin has a low affinity for oxygen so oxygen readily dissociates with haemoglobin. Thus the percent saturation is low.
Describe the loading, transport and unloading of oxygen in areas with a high partial pressure of oxygen. (In relation to the oxyhaemoglobin dissociation curve)
Haemoglobin has a high affinity for oxygen. So oxygen readily associates with haemoglobin. So percent saturation is high.
Explain how the cooperative nature of oxygen binding results in a sigmoid oxyhaemoglobin dissociation curve.
Binding of first oxygen changes tertiary/quaternary structure of haemoglobin. This uncovers the haem group binding sites making further binding of oxygens easier.
