7.1 - Haemoglobin Flashcards
What are haemoglobin’s?
Preotein molecules with a quaternary structure that has evolved to make it efficient at loading oxygen under one set of conditions but unloading it under a different set of conditions
What is the primary structure of haemoglobin?
The sequence of amino acids in the four polypeptide chains
What is the secondary structure of haemoglobin?
In which of the 4 polypeptide chains is coiled into a double helix
What is the tertiary structure of haemoglobin?
In which each polypeptide chains is coiled is folded into a precise shape - an important factor in its ability to carry oxygen
What is the quaternary structure of haemoglobin?
- In which all four polypeptides are linked together to form an almost spherical molecule
- each polypeptide is associated with a haem group - which contains a ferrous ion
- each Fe2+ ion can combine with a single oxygen molecule making a total of four 02 molecules that can be carried by a single haemoglobin molecule in humans
What is the process by which haemoglobin binds with oxygen called? (Two names)
- loading
- associating
What is the process by which haemoglobin releases its oxygen called? (Two names)
- unloading
- dissociating
Haemoglobin’s with a high affinity for oxygen what?
- Take up oxygen more easily
- realise it less easily
Haemoglobins with a low affinity for oxygen what?
- take up oxygen less easily
- realise it more easily
What are the two things haemoglobin must be efficient at
- readily associating with oxygen
- readily dissociating from oxygen
How can haemoglobin load and unload with oxygen easily when they contradict each other?
It changes its affinity for oxygen under different conditions
What does affinity mean?
Chemical attraction
How can haemoglobin change its affinity?
Its shape changes in the presence of certain substances, such as carbon dioxide, in the presence of carbon dioxide, the new shape of the haemoglobin molecule binds more loosely to oxygen. As a result haemoglobin releases its oxygen
