Haemoglobin Flashcards
Where is haemoglobin found?
• erythrocytes
There are many chemically similar types of haemoglobin found in many different organisms.
Found in all vertebrae, earthquakes, starfish, some insects and some plants and some bacteria
Describe and explain the structure and function of haemoglobin
• protein with a quaternary structure (has 4 polypeptide chains
• Has 4 subunits (2 alpha and 2 beta). Each subunit has 1 polypeptide chain and 1 haem group which contains a single iron ion
• the iron ion has a high affinity for oxygen
• each haemoglobin can bind to 4 oxygen molecules when 100% saturated
What does
Haemoglobin bind to in the lungs?
Binds to oxygen to form oxyhemoglobin. This is a reversible reaction
What is association/loading?
The process by which haemoglobin binds with oxygen, takes place in lungs in humans
What is dissociation/unloading?
The process by which haemoglobin releases oxygen. In humans this takes place In the respiring tissues
What is partial pressure?
The concentration of a gas
What is partial pressure of oxygen in regards to mass transport?
A measure of oxygen concentration in the tissues
What does a oxyhaemoglobin dissociated curve show?
How saturated haemoglobin is with oxygen at any given partial pressure of oxygen
What shape is a dissociation curve?
An S shape as it is a sigmoidal curve
What happens regarding haemoglobin at low partial pressures of oxygen?
• haemoglobin does not easily bind because the haem groups are in the centre of the haemoglobin which makes it difficult for the oxygen to bind with it
• results in a low saturation level at low oxygen partial pressures
What happens regarding haemoglobin as partial pressures of oxygen increases?
• diffusion gradient into the haemolglobin increases
• means taht eventually an oxygen molecule will associate with one of the haem groups
• results in a conformational change in shape of the haemoglobin molecule and makes it easier for more oxygen molecules to associate with other haem groups = cooperative binding as haem groups are exposed
• therefore gradient of curve increases as the oxygen partial pressure does
What happens regarding haemoglobin at high partial pressures of oxygen?
• haemolytic had a higher affinity for oxygen and more readily associated/ binds
• graph plateaus because it is difficult for all the haemoglobin molecules to become 100% saturated
What is partial pressure of carbon dioxide?
Measure of carbon dioxide concentration in a cell
How does high partial pressures of carbon dioxide affect the unloading of oxygen?
Haenolglobin unloads its oxygen more readily at a higher partial pressure of carbon dioxide by lowering its affinity for oxygen
What is the Bohr effect? Why does it happen?
When the dissociation curve shifts to the RIGHT
It happens due to cells producing CO2 when they respire raising pCO2, increasing the rate at which oxyhaemoglobin dissociates to form haemoglobin and oxygen.
The Bohr effect therefore results in more oxygen being released when more carbon dioxide is produced. Means when exercising the muscles can be supplied with more oxygen for continued aerobic respiration
What type of haemolgobin do organisms in a low oxygen environment have? What does the suction curve look like compared to humans?
• haemoglobin with a higher affinity for oxygen than human haemoglobin
• because there isn’t much oxygen available, so the haemoglobin has to be very good at loading any available oxygen
The dissociation curve is to the LEFT of humans
eg lugworm
What type of haemolgobin do organisms with high activity levels have? What does the dissociation curve look like compared to humans?
• haemolgobin has a lower affinity for oxygen than human haemolglobin because they need their haemoglobin to easily unload oxygen so its available to use
The dissociation curve is to the RIGHT of humans
eg hawk
What type of haemolgobin do small organisms have? What does the dissociation curve look like compared to humans?
• small mammals have a higher surface area:vol ratio meaning they lose heat quicker so have a high metabolic rate to help them keep warm therefore have a high oxygen demand
• they have haemoglobin with a lower affinity for oxygen then human haemoglobin because they need there haemoglobin to easily unload oxygen, so it’s available to use
The dissociation curve is to the RIGHT of humans
eg rat
