Haemoglobin Flashcards
Haemoglobin structure
Quaternary structure with two beta chains and two Alpha chains
Each polypeptide chain has a haem group
Each haem group is made of iron 2+
Haemoglobin can have up up to 4 haem groups
Haemoglobin has an affinity to oxygen
Affinity
chemical attraction to oxygen
Partial pressure of oxygen
the proportion of oxygen in a mixture of gases or a solution
The more oxygen there is in the blood. The more oxygen is loaded onto haemoglobin haemoglobin because more saturated as greater affinity so less readily unloads
Loading
when oxygen is taken up by haemoglobin
Unloading/ dissociation
when oxygen is released all given up by haemoglobin
Oxygen dissociation curve
Y axis= percentage of saturation of haemoglobin with oxygen
X axis= partial pressure of oxygen
High saturation in the lungs at 100%
Lower saturation in the tissues were at rest as respiration means oxygen is used up
Always a S shape known as sigmoid curve= this is because of cooperative binding
Cooperative binding
when first oxygen molecule binds to the tertiary structure of haemoglobin this exposes the second and third oxygen binding site making it easier for the second and third oxygen molecule to bind and load
Partial pressure in the lungs
high partial pressure as around 13 kPa
Haemoglobin has a higher affinity for oxygen at a high partial pressure
Haemoglobin becomes almost fully saturated
Partial pressure in respiring tissues.
Partial pressure in the tissues is lower as it’s about 5 kPa.
Haemoglobin has a lower affinity for oxygen as Oxy haemoglobin starts to breakdown and unload oxygen so it could be readily used for aerobic respiration so readily unloads
Effect of carbon dioxide concentration= bohR shift ( RIGHT )
When carbon dioxide dissolves in the blood, it makes the blood more acidic lowering the pH
This alters the tertiary structure of haemoglobin so has a lower affinity to oxygen and higher affinity to CO2
More oxygen is unloaded from haemoglobin at same partial pressure
Oxygen dissociation curve for high metabolic rates and small animals
Smaller mammals have a larger surface of volume ratio some more heat loss due to respiration as greater respiration
Haemoglobin readily dissociate, which means it has a lower affinity to oxygen so the graph will move to the right hand side
Oxygen dissociation curve for Species that live in environments where environmental partial pressure is low such as bottom of lakes or high altitude and foetus
Dissociation curve shifts to the left-hand side as haemoglobin has a higher affinity for oxygen
It becomes fully saturated at lower partial pressure and rapidly unload its oxygen when the haemoglobin passes into the tissues for respiration
Feotus haemoglobin has a similar shape curve
