unit 3, haemoglobin and dissociation curve Flashcards
what is the structure of haemoglobin?
-quaternary structure
-4 polypeptide chains
-each chain has an iron ion, which is where oxygen binds
-globular
-shperical
What is the function of haemoglobin?
allows red blood cells to transport oxygen from the lungs to all other parts of the body.
what is affintiy of haemoglobin with oxygen?
the ability of haemoglobin to attract or bind to oxygen
what is saturation of haemoglobin with oxygen?
haemoglobin holding the maximum amount of oxygen it can
what is loading/associating?
haemglobin taking on oxygen
what is unloading/dissociating?
heamoglobin releasing oxygen
what happens on the oxyhaemoglobin dissociation curve at lower partial pressure?
There is lower affinity, so there is higher unloading of oxygen. This occurs at muscle tissues when they are respiring.
what happens on the oxyhaemoglobin dissociation curve at higher partial pressure?
There is higher affintiy, and higher saturation, lots of loading of oxygen. This happens at the Alveoli.
what is co-operative binding?
the 1st binding slightly changes the 3D shape, the quaternary structure, allowing further oxygen to bind/load easier.
what is the Bohr effect?
-When there is high concentration of Carbon Dioxide it causes there to be a lower affinity of heamoglobin for oxygen, becasue the acidic carbon dioxide changes the shape of haemoglobin slightly to prevent it from loading as much oxygen. This is an advantage for respiring.
what happens to affinity when there is low amount of carbon dioxide?
-affinity for oxygen increases and a higher partial pressure is needed to bind effectively.
which way does the curve shift if there is high amounts of carbon dioxide?
to the right
-remember,right release
will the gradient be high or low when there is more carbon dioxide?
low, it is not as steep
does a fetus have a high of low affinity for oxygen? example
high affinity
-because fetus are unable to inhale or exhale they have a high affinity to load as much oxygen as possible
does a Llama living at high altitudes have a high or low affinity for oxygen? example
high affinity
-due to lack of oxygen at high altitudes, needs to load as much as possible
does a Dove have a high or low affinty for oxygen? example
low affinity
-due to Doves constantly flying they need to have constant respiration, therefore the affinity is low
does a Earthworm have a high or low affinity for oxygen? example
high affinity
- due to lack of oxygen underground they need to have high affinity to load as much oxygen as possible
on the oxygen dissociation curve what happens at each stage 1-4?
1) the partial pressure is low, the gradient is shallow, therefore the oxygen has been unloaded so the shape is tight. the tight shape makes it harder for other oxygen to bind, low affinity. e.g.) at muscle
2) the binding of the second oxygen changes the quaternary shape of the haemoglobin, making it easier for the other oxygen to bind. the affinity is increasing and there is a positive small increase in the gradient. there is co-operative binding. High affinity.
3)binding of the third oxygen causes the quaternary structure to loosen , the affinity has further increased. less increase of partial pressure to bind oxygen.
4)binding becomes harder again, because its hard to locate the last lost unbound site. the affinity is high, but there is a shallow gradient.
How does an increase in carbon dioxide affect haemoglobin?
-means there is more carbonic acid, which changes the quaternary shape of haemoglobin. Because there is protons that cause the release of oxygen
when carbon dioxide is high, is the pH of blood high or low?
The pH of blood is lowered from high PCo2, due to the carbonic acid that is formed. acid is low on the pH scale.
at what stage does deoxyhaemoglobin become oxyhaemoglobin?
stage 4, when all oxygen has binded to the haemoglobin.
where is carbon dioxide carried?
dissolved, in the blood plasma.
