mass transport in animals (3.4) Flashcards
describe the structure of haemoglobin
-globular protein
-has a quaternary structure made up of 4 polypeptide chains
-each chain has a haem group which contains iron that oxygen binds to (therefore haemoglobin can hold up to 4 oxygen molecules)
what is the function of haemoglobin
responsible for binding oxygen in the lungs and transporting the oxygen to respiring tissues
how does partial pressure affect haemoglobin’s affinity
at a high partial pressure of oxygen (e.g alveoli) haemoglobins affinity for oxygen increases so oxygen is readily loaded.At a low partial pressure(e.g respiring tissue) the affinity for oxygen decreases so oxygen is readily unloaded.
how can saturation affect haemoglobins affinity
-it is hard for the first oxygen molecule to bind however once it has bound haemoglobins shape changes due to cooperative binding and it is easier for the other oxygen molecules to bind as affinity for oxygen is increased.
-It is also unlikely the 4th oxygen molecule will find a binding site as the haemoglobin is almost fully saturated.
what is the bohr effect
When a high concentration of CO2 causes the oxyhaemoglobin curve to shift to the right
-the affinity for O2 is reduced because the acidic CO2 causes the shape of haemoglobin to slightly change.
how is fetal haemoglobin(HbF) different to adult haemoglobin (HbA)
HbF curve shifts left as it has higher affinity for oxygen compared to HbA as HbF must have higher affinity in order to load oxygen from the adult
how will the oxyhaemoglobin curve look for an animal that lives at a low partial pressure of oxygen
curve will shift left as animal will have a high affinity for oxygen so it can be readily loaded
how would the oxyhemoglobin curve look for an animal with a high metabolic rate
curve shifts right so affinity for oxygen is lowered this means it can be readily offloaded to respiring tissues
