Hope this helps :)

HideShow resource information
Preview of Haemoglobin

First 207 words of the document:

Ellianna Gibbs L6.03
The role of haemoglobin is to transport oxygen.
Haemoglobin (Hb) Molecules
Primary Structure: 4 interlocking polypeptides.
Secondary Structure: Each chain is coiled into a helix.
Tertiary Structure: Each polypeptide chain is folded into a precise shape.
Quaternary Structure: Each polypeptide is associated with a haem group.
Every Haem group can carry an O2 molecule. The O2 fits into a complementary
shaped binding site on the Hb.
Hb + 4O2 HbO8 How much had been combined with oxygen.
Where ppO2 is high, Hb has a high
affinity for O2 (how "likely" it will
combine)so it has a high saturation of
Amount of O2 available.
When ppO2 is low Hb has a low affinity for O2 which means it dissociates with
oxygen rather than combines with it. That's why it has a low saturation of oxygen.
O2 dissociates in active cells
O2 combines in the lungs ­ which as a higher ppCO2 & water vapour. In the
presence of carbon dioxide the shape of haemoglobin binds more loosely to
oxygen which makes haemoglobin release its oxygen.

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

Ellianna Gibbs L6.03
The graph is s-shaped because
when Hb combines with the first
oxygen molecule so it is easier for
other molecules to join too. As it
starts to become more fully
saturated it becomes harder for
more oxygen to join. As a result the
curve has a steep bit in the middle
where it's easier for oxygen to join
and shallow bits at each end where
it is harder for oxygen to combine.
It's hard to lose 1 molecule of O2.…read more

Page 3

Preview of page 3

Here's a taster:

Ellianna Gibbs L6.03
Loading, transport and unloading of oxygen
At the gas-exchange surface CO2 is constantly being removed.
The pH is raised due to the low level of CO2.
The higher pH changes the shape of haemoglobin into one that loads oxygen
The shape increases the affinity for oxygen so it's not released during
In the tissues CO2 is produced by respiring cells.
CO2 is acidic in solution so the pH of the blood in the tissues is lowered.…read more


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »