7.1- HAEMOGLOBIN Flashcards
What are the haemoglobins?
group of chemically similar molecules found in wide variety of organisms
What kind of molecules are haemoglobins?
protein molecules
What kind of structure do haemoglobins have?
quaternary structure
Why has the haemoglobins evolved a quaternary structure?
make it efficient at loading oxygen under one set of conditions but unloading under different set of conditions
What is the primary structure of haemoglobin?
sequence of amino acids in the four polypeptide chains
What is the secondary structure of haemoglobin?
each of the polypeptide chains coiled into helix
What is the tertiary structure of haemoglobin?
each polypeptide chain folded into precise shape- important factor in its ability to carry oxygen
What is the quaternary structure of haemoglobin?
all four polypeptides linked together to form almost spherical molecules
What is each polypeptide associated with in haemoglobin?
with a haem group
What does the haem group of haemoglobin contain?
ferrous (Fe2+) ion
What can each Fe2+ ion of the haem group in haemoglobin combine to?
can combine with single oxygen molecule, making total of 4 oxygen molecules that can be carried by single haemoglobin molecules in humans
What is the process by which haemoglobin binds with oxygen called?
loading or associating
Where does loading/associating happen in humans?
in the lungs
What is the process by which haemoglobin releases it oxygen called?
unloading or dissociating
Where does unloading/ dissociating happen in humans?
in tissues
What does haemoglobin with a high affinity for oxygen do?
take up oxygen more easily, but release it less easily
What does haemoglobin with a low affinity for oxygen do?
take up oxygen less easily, but release it more easily
What is the role of haemoglobin?
transport oxygen
What must haemoglobin do to be efficient at transporting oxygen? (2)
readily associate with oxygen at surface where gas exchange happens
readily dissociate from oxygen at those tissues requiring it
How is haemoglobin able to readily associate + dissociate from oxygen?
it changes its affinity (chemical attraction) for oxygen under different conditions
How does haemoglobin’s affinity for oxygen change?
its shape changes in presence of certain substances i.e. carbon dioxide
What happens to haemoglobin in the presence of carbon dioxide?
new shape of haemoglobin molecules binds more loosely to oxygen
so haemoglobin releases its oxygen
Are there different types of haemoglobin?
yes
Why do different haemoglobins have different affinities for oxygen?
lies in shape of molecules
What is different about the haemoglobin of each species?
different tertiary + quaternary structure and hence different oxygen binding properties
