B - 2 - Haemoglobin Flashcards
What is haemoglobin?
An oxygen carrying protein found in red blood cells
Describe the structure of haemoglobin
- Quaternary structure
- Has 4 polypeptide chains
- each chain has a haem group which contains an iron ion which gives haemoglobin its red colour
How many molecules of oxygen can haemoglobin carry and why?
four, because each molecule binds to an iron ion, and there are for iron ions, one for each polypeptide chain
What is oxyhemoglobin?
The molecule formed when oxygen binds to haemoglobin
What is loading of oxygen (onto haemoglobin)
What is the other name for this process?
- The action of an oxygen molecule binding with a haemoglobin molecule
- Association
What is unloading of oxygen (from haemoglobin)
What is the other name for this process?
The action of an oxygen molecule being released from a haemoglobin molecule
What is affinity for oxygen?
The tendency a molecule has to bind with oxygen
What is the partial pressure of oxygen?
A measure of oxygen concentration
Describe the process that happens when there is a high partial pressure of oxygen
When there is a higher partial pressure of oxygen, oxygen loads onto haemoglobin to form oxyhaemoglobin
Describe the process that happens when there is a low partial pressure of oxygen
Oxyhaemoglobin unloads it oxygen
Describe what happens in terms of oxygen association in the alveoli?
- There is a high concentration of oxygen
- Therefore there is a high partial pressure
- So there is a high affinity
- So oxygen loads
Why does association take place at the alveoli?
Because this is where oxygen enters the lungs
Describe what happens in terms of oxygen dissociation in respiring tissues
- There is a low oxygen concentration
- Therefore a low partial pressure
- so there is a low affinity
- so oxygen unloads (dissociation)
What is the Bohr effect
An affect by which an increase of carbon dioxide in the blood results in a reduction of haemoglobin affinity for oxygen
What is the partial pressure of carbon dioxide?
A measure of carbon dioxide concentration
How does carbon dioxide affect oxygen unloading?
When there is a higher partial pressure of carbon dioxide, haemoglobin gives up its oxygen more readily - dissociation takes place at a higher rate
How do low oxygen environments effect haemoglobin and affinity
Organisms that live in low oxygen environments have haemoglobin with a higher affinity for oxygen
How do high activity levels in organisms affect haemoglobin and association?
They have a lower affinity for oxygen as they need their haemoglobin to unload oxygen more easily so it is available for them to use
How does the size of an organism affect haemoglobin and association?
Small mammals have a higher surface area to volume ratio than large animals so they lose heat quickly, so they have a high metabolic rate to keep them warm - so they have high oxygen demand. This means they have a lower affinity for oxygen as they need they haemoglobin to easily unload to meet their oxygen demand.
Describe the placing of a dissociation curve of organisms in low oxygen environments in comparison to humans
Their dissociation curve is to the left
Describe the placing of a dissociation curve of organisms with high activity levels in comparison to humans
Their dissociation curve is to the right
Describe the placing of a dissociation curve of organisms that are small in comparison to humans
Their dissociation curve is to the right
