7.1: Haemoglobin Flashcards
What is the protein structure of a Haemoglobin molecule
Primary structure - sequence of amino acids in the 4 polypeptide chains
Secondary structure - Each polypeptide chain is coiled into a helix
Tertiary structure - Each polypeptide chain is folded into a precise shape - important for oxygen carrying
Quaternary structure - All 4 polypeptides are linked together in an almost spherical molecule. Each polypeptide is associated with a haem (fe2+) molecule which can combine with a single o2 molecule
Each haemoglobin molecule can carry 4 Oxygen molecules
What is the loading of oxygen and where does this occur
The process by which Haemoglobin binds with oxygen
Also known as Associating. This takes place in the lungs
What is the un-loading of oxygen and where does this occur
The process by which Haemoglobin releases its oxygen
Also known as dissociating. This takes place at respiring tissues
What does a high affinity for oxygen mean
That haemoglobin will more readily bind with oxygen, however will less readily release it
What does a low affinity for oxygen mean
That haemoglobin will less readily bind with oxygen, however will more readily release it
What is the role of haemoglobin
- To readily associate with oxygen at the surface where gas exchange takes place
- Readily dissociate from oxygen at those tissues requiring it
What is the property of haemoglobin that makes it achieve its role
It is able to change its affinity for oxygen under different conditions
How does haemoglobin change its affinity
When in the presence of CO2, it changes shape. The changed shape binds more loosely to oxygen, as a result haemoglobin releases its oxygen to the tissues surrounding it
Where is CO2 concentration highest
Next to respiring tissues, where oxygen is needed. Therefore oxygen dissociates
Where is CO2 concentration lowest
On the surface of gas exchange, lungs, where Oxygen takes up the majority. Oxygen therefore associates
Why re there different haemoglobins
Each species produces haemoglobin with a slightly different amino acid sequence. Therefore it has a different tertiary/quarternary structure and hence different oxygen binding properties.
