# Oxygen Affinity A-level Biology Edexcel

What exactly is Oxygen Affinity? Can I have a fleshed-out description of it regarding haemoglobin?
I like to think of affinity to oxygen as how likely oxygen will bind to the Hb. If you have a high affinity it will be more likely to bind, if it’s low then it’s less likely.

The oxygen dissociation curve is shaped like an s. There’s a steep part in the middle which is effective because basically any small change in pressure can have a big change in affinity.

At lower pressure it is hard for the oxygen to bind to the Hb as it is bonded tightly together, as the pressure increases oxygen is more likely to bind, and once one has the Hb opens up more and it’s easier for more oxygen to bind.

I do WJEC (and this was the essay question in my recent as exam), but we have to know about the Bohr effect and Hb in a foetus/high altitude, so I’ll go intro that too.

The Bohr effect happens when there’s too much CO2 and moves the curve to the right. Hb has less of an affinity to oxygen and is more likely to release oxygen to the tissue cells to be used. This can happen when there’s a lot of respiration (like exercise)

I’m a foetus/high altitude there’s a higher affinity for oxygen, meaning the Hb will load more oxygen than it is likely to release. I think this is because there’s less oxygen in the air that the Hb wants to store the oxygen to use in the tissues later.the curve moves to the left for this.
(edited 1 month ago)
Original post by study23!
I like to think of affinity to oxygen as how likely oxygen will bind to the Hb. If you have a high affinity it will be more likely to bind, if it’s low then it’s less likely.
The oxygen dissociation curve is shaped like an s. There’s a steep part in the middle which is effective because basically any small change in pressure can have a big change in affinity.
At lower pressure it is hard for the oxygen to bind to the Hb as it is bonded tightly together, as the pressure increases oxygen is more likely to bind, and once one has the Hb opens up more and it’s easier for more oxygen to bind.
I do WJEC (and this was the essay question in my recent as exam), but we have to know about the Bohr effect and Hb in a foetus/high altitude, so I’ll go intro that too.
The Bohr effect happens when there’s too much CO2 and moves the curve to the right. Hb has less of an affinity to oxygen and is more likely to release oxygen to the tissue cells to be used. This can happen when there’s a lot of respiration (like exercise)
I’m a foetus/high altitude there’s a higher affinity for oxygen, meaning the Hb will load more oxygen than it is likely to release. I think this is because there’s less oxygen in the air that the Hb wants to store the oxygen to use in the tissues later.the curve moves to the left for this.

Thank you. This is a very clear description.