as level biology unit 1 - exam in 10 days!! - oxygen affinity, binding, haemoglobin.. Watch

JamesStanley
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Hi can someone please explain the whole section of oxygen binding to haemoglobin and high/low affinity and all that stuff because i cant get my head around it all... ive tried and tried and tried but it aint workin!! please include a question or two in your reply as to put it into context for me and how to answer exam questions....

much appreciated :-)
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ahmad97h
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What part do you find difficult exactly? The Bohr shift, oxygen dissociation curve or fetal haemoglobin?
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JamesStanley
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(Original post by ahmad97h)
What part do you find difficult exactly? The Bohr shift, oxygen dissociation curve or fetal haemoglobin?
all 3 really..

1) is the bohr shift where there are two curves and them being in different places means its because one has higher affinity or something..?

2) is oxygen disassociation where oxygen leaves haemoglobin, just going on the name of it..?

3) fetal haemoglobin ive never heard of that (or at least cant remember!!)

thanks a lot :-)
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afmillward
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Affinity is how well 2 things combine together. So in this context, when haemoglobin has a high affinity for oxygen, then oxygen combines easily with haemoglobin.
In terms of the oxygen binding itself, it can bind to haemoglobin because in each molecule of haemoglobin, there are 4 iron ions. Each iron in can bind to one oxygen molecule, so there can be a maximum of 4 oxygen molecules bound to haemoglobin. Therefore, when 4 oxygen molecules are associated with haemoglobin, it is said to be 100% saturated. The percentage of saturation of haemoglobin depends on the amount of oxygen available and this is measured in partial pressures of oxygen. From this, we get the oxygen dissociation curve. This shows us that at higher partial pressures of oxygen, haemoglobin is more saturated.
At a respiring tissue (where lots of oxygen is being used up), the partial pressure of oxygen is low and so is the saturation of haemoglobin. This is because haemoglobin is getting rid of oxygen so that it can be used. The dissociation curve varies for different organisms.
Hope this helps a bit, any more questions just ask
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afmillward
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The Bohr shift occurs where there is a high amount of carbon dioxide. This lowers the affinity of haemoglobin for oxygen, and the dissociation curve moves to the right because haemglobin cannot absorb (associate) oxygen very easily and instead, it releases (dissociates) oxygen very easily.
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ahmad97h
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1. the bohr shift is what happens when there are high levels of Carbon Dioxide. the affinity for Oxygen decreases and so more Oxygen is released where there is more CO2. This is important as it means that were cells are respiring more, they are also receiving more oxygen. the curve is to the right.
2. Oxygen dissociation is when haemoglobin releases Oxygen
3. Fetal haemoglobin (baby haemoglobin) has a higher affinity for Oxygen than adult haemoglobin as it has competition from the mother. it is more likely to receive higher amounts of Oxygen. The curve is to the left of an adult haemoglobin curve.
Hope this helps!
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