The Student Room Group

Have i explained how the Bohr effect can impact the structure of haemoglobin correct?

an Increased amount of co2 produced due to respiration diffuses into red blood cells where it reacts with water to form carbonic acid, catalysed by carbonic anhydrase. Carbonic acid dissociates into hydrogen carbonate ions and hydrogen ions which Lowers blood ph, So haemoglobin acts as a buffer by binding to hydrogen ions forming haemoglobinic acid which prevents a further fall in pH This causes haemoglobins shape to change slightly Reducing hbs affinity for oxygen Resulting in faster unloading of oxygen to respiring tissues
(edited 1 month ago)
Original post by D17Hio
an Increased amount of co2 produced due to respiration diffuses into red blood cells where it reacts with water to form carbonic acid, catalysed by carbonic anhydrase. Carbonic acid dissociates into hydrogen carbonate ions and hydrogen ions which Lowers blood ph, So haemoglobin acts as a buffer by binding to hydrogen ions forming haemoglobinic acid which prevents a further fall in pH This causes haemoglobins shape to change slightly Reducing hbs affinity for oxygen Resulting in faster unloading of oxygen to respiring tissues

Seems explained pretty well
Reply 2
Accurate enough at the tissue level where there's increased CO2 due to aerobic respiration. But what about in the lung? :smile:
Reply 3
Original post by AriTem
Accurate enough at the tissue level where there's increased CO2 due to aerobic respiration. But what about in the lung? :smile:

In the lungs haemoglobin would have a higher affinity for oxygen and so more loading would take place because the lungs has a higher partial pressure of oxygen and lower partial pressure of c02 compared to respiring tissues so the change in shape of haemoglobin is only present during respiration in tissues
Reply 4
Original post by D17Hio
In the lungs haemoglobin would have a higher affinity for oxygen and so more loading would take place because the lungs has a higher partial pressure of oxygen and lower partial pressure of c02 compared to respiring tissues so the change in shape of haemoglobin is only present during respiration in tissues

not quite accurate. there's also a change in shape for Hb at the lung. not sure you need to know it in that much detail but essentially the change from taut to relaxed haem at the lung is driven by the higher pO2 pressures. initial O2 binding causes haem to change from taut to relaxed form progressively increasing (with increased O2 binding) hemoglobin’s affinity for oxygen at each of the remaining binding sites. taut form has a reduced O2 affinity as you have mentioned vs the relaxed form which has a higher O2 affinity. logically speaking, if there is a change in form at the tissue level, then there must be an associated reversal of the change somewhere else (i.e. lung). otherwise we would be left with taut haem only.
Reply 5
Original post by AriTem
not quite accurate. there's also a change in shape for Hb at the lung. not sure you need to know it in that much detail but essentially the change from taut to relaxed haem at the lung is driven by the higher pO2 pressures. initial O2 binding causes haem to change from taut to relaxed form progressively increasing (with increased O2 binding) hemoglobin’s affinity for oxygen at each of the remaining binding sites. taut form has a reduced O2 affinity as you have mentioned vs the relaxed form which has a higher O2 affinity. logically speaking, if there is a change in form at the tissue level, then there must be an associated reversal of the change somewhere else (i.e. lung). otherwise we would be left with taut haem only.

Yh i dnt need to know that but thanks
Reply 6
Original post by AriTem
Accurate enough at the tissue level where there's increased CO2 due to aerobic respiration. But what about in the lung? :smile:

I'm a bit confused thought is it drop in pH which causes the hbs shape to change or the haemoglobin binding to oxygen to form haemoglobinc acid
Reply 7
at the tissue it's the drop in pH that causes the change from relaxed to taut haem. at the lung the higher pO2 and lower pCO2 drives the dissociation of the CO2 from haem. there are 4 binding sites, the displacement at the first site causes taut haem towards the relaxed form (each subsequent O2 binding causes more relaxation of the haem leading to increased O2 affinity). so haem flips between taut and relaxed form

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