MuadElsmuai
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Who can help me to explain the answer to this question Calculate the percentage of amino acids that are different in adult and fetal haemoglobin?The answer in the marking scheme is 13.6 but I didn't get how they calculated it 😕
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macpatgh-Sheldon
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I think you will need some more info, which I don't believe the examiner would expect you to google. Please upload the whole Q here - then I am sure I can help you.

I don't think anyone would expect you to know this but in foetal Hb [HbF] the amino acid at position 136 in the gamma chain is replaced by alanine or glycine [adult haemoglobin [HbA] has 2 alpha chains and 2 beta chains, WHEREAS in HbF there are 2 alpha chains and 2 gamma chains].

The alpha chain is 141 a.a.-s long, while both the beta and gamma chains are 146 a.a. long.

So, if we consider this one substitution [above] there would be a difference of 2 a.a.-s out of [141 X 2] + [146 X 2], so 2 out of 574, which is approx. 0.4 % - I have no idea how the examiner calculated the massive %age. - SORRY!

Can you check for OP please Jpw1097 - thanks!

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