haemoglobin Flashcards
what is the structure of haemoglobin?
protein with a quaternary structure made of 4 polypeptide chains
how many haem groups does a haemoglobin have and what do these do?
4 each with an iron ion
the iron ion has a charge so it can associate with oxygen to form oxyhaemoglobin
so 4 oxygen molecules per haemo
why is oxygen loaded in the lungs?
there is a high partial pressure of oxygen in the lungs
haemo has a high affinity for oxygen
oxygen associates with iron ions in the haem groups to form oxyhaemoglobin
what does the binding of the first oxygen molecule to the haemo cause?
changes the tertiary structure so the second binding site (haem group) is revealed so it is easier for the next oxygen to associate
so haemo becomes fully saturated
cells of tissues carry out respiration, what does this mean for ppO2?
lowers partial pressure of oxygen in tissues and increases carbon dioxide levels
what does CO2 produced by respiration do for haemo?
diffuses into red blood cells and reacts with water, this is catalysed by carbonic anhydrase
forms carbonic acid which lowers the pH
acid dissociates to release H+ and these are buffered by haemo
higher CO2 levels lower the affinity of haemo for oxy
what does haemoglobin having a lower affinity for oxygen mean for the curve?
causes a Bohr shift where the oxygen dissociation curve shifts right
at a particular ppO2 there is a greater dissociation of oxy-haemoglobin (oxygen more readily released)
so MORE oxygen released to maintain rates of aerobic resp
what does exercise require and what does this produce?
high rates of respiration to make more ATP for greater muscle contraction so CO2 produced which causes a Bohr shift as the curve shifts right
what is the benefit of the curve shifting to the right during exercise?
haemo has lower affinity for oxy at ppO2 found in tissues so more oxyhaemoglobin dissociates at that ppO2
high rates of aerobic resp maintained and anaerobic resp prevented which prevents muscle fatigue
where is myoglobin found and what does it act as?
in the muscles and acts as a store for oxygen
how is the curve changed for myoglobin and what does this mean?
shifted to left so myoglobin has a high affinity for oxygen than haemoglobin so oxygen dissociates less readily
at a particular ppO2 less oxyhameo dissociates and it only dissociates when there’s a significant drop in ppO2
releases more oxygen to tissues which have low ppO2 to maintain aerobic resp and prevent anaerobic resp that leads to muscle fatigue
how does the dissociation curve change for organisms with high rates of resp?
shifted to right so haemo has a lower affinity for oxygen at the ppO2 found in respiring tissues
at this ppO2, oxyhaemoglobin dissociates rapidly and more oxygen is released to tissues
maintains high rates of aerbic resp
why is a high rate of respiration needed for organisms with a high SA:V ratio?
with a smaller SA: vol ratio more heat is lost so higher rates of respiration are required to release heat and replace the heat that is lost- this maintains body temp
how does the curve of foetal haemoglobin compare to the curve of adult haemoglobin?
shifted to left
foetal haemoglobin has a higher affinity for oxygen than the mothers haemoglobin
enables oxygen transfer from the mother to the foetus
how is the dissociation curve for animals that live in environments with low ppO2 e.g. high altitude and under ground?
curve shifted to left
haemoglobin has a higher affinity for oxygen at lower ppO2
so at lower pO2 the haemoglobin is fully saturated
so enough oxygen is transported to respiring tissues for required rates of aerobic respiration
how is the dissociation curve for animals with times when oxygen cannot be obtained, e.g. diving mammals and tidal organisms?
curve shifted to left
haemoglobin has a higher affinity for oxygen at lower ppO2
oxyhaemo only dissociates when there is significant drops in the ppO2
this maintains aerobic respiration when oxygen cannot be obtained from the environment
what are 4 structures of red blood cells that make it adapted for its function of carrying oxygen from lungs to respiring tissues?
thin cell membrane
no nucleus
250 million molecules of haemoglobin
biconcave shape
what is the benefit of a red blood cell having a thin cell membrane?
short diffusion pathway for oxygen to diffuse in and out of the cell quickly
what is the benefit of red blood cells having no nucleus?
more haemoglobin molecules within each cell so more oxygen can be transported
what is the benefit of the biconcave shape of red blood cells?
greater surface area for uptake or release of oxygen (faster rate of diffusion)
