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biology haemoglobin helppp

Explain how haemoglobin transports oxygen?
Hi, if I remember right, you are a "detail freak" like myself (sorrrrrrry!! :colondollar:, although it's a good thing!).

OK down to nerdiness!
Haemoglobin (Hb) is made of four globin chains (all proteins); in the adult they are 2 alpha chains (141 amino acid residues each) and two beta chains (146 amino acid residues each) with a ferrous iron in the centre.

The oxygenation of one globin results in greatly increased affinity to O2 of the other globins, which means that oxygenation is greatly enhanced by its initiation, and vice versa [affinity reduces exponentially with the start of deoxygenation]. These features explain the sigmoid shape of the oxygen dissociation curve of Hb.

When O2 binds to Hb, there is a twisting of the alpha-1/beta-2 junction [by breakage of salt bridges]; this is crucial to the process of O2 binding .

Also look up the "Bohr shift".

M
Further to the above post, the binding of the 1st O2 molecule to the Haem group (Fe2+ ion) causes a conformational change in the 3D tertiary structure of Hb, unmasking the 2nd and 3rd O2 binding sites, making it easier for the 2nd and 3rd O2 molecules to bind. These OxyHb groups then ‘get in the way’ of the 4th bonding site (called Steric Hindrance) making it much more difficult for O2 to bind to this 4th binding site.
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Avatar for laura273
laura273
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thanks guys for your help, is there a more simple way of answering the question.
haha yes i like things to be detailed but i want to keep it simple and clear when revising

also what this question below

Explain the purpose and process of primary haemostasis following an incision.
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Avatar for idk01
idk01
20
A simpler explanation of how haemoglobin transports oxygen is that the oxygen molecule binds to the iron in the haem group (prosthetic group) on each of the four chains.
Original post by laura273
thanks guys for your help, is there a more simple way of answering the question.
haha yes i like things to be detailed but i want to keep it simple and clear when revising

also what this question below

Explain the purpose and process of primary haemostasis following an incision.
Haemostasis (= blood clotting)

Purpose: A] To stop uncontrolled bleeding from injury site
………….B] To prevent germs entering body

Process: Exposure of blood to air due to cut + contact with external cells ------> 1st clotting factor -----> becomes active enzyme for 2nd clotting factor (thousands of these activated) ----- millions of 3rd factor activated etc etc.

This chain of reactions is called a cascade reaction.

Final step: prothrombin ----> thrombin -----> fibrin clot

Platelets help in this process (fibrin entangles with them)

If some clotting factors are deficient ----> uncontrolled bleeding e.g. haemophilia, which runs in royal family.

I have tried to keep it short and simple for you this time! :smile:
M

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