In sickle cell anaemia glutamic acid is replaced by valine. Which one of the following triplets codes for valine?
A
GGG
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B
AAG
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C
GAA
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D
GUG
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Solution
The correct option is D GUG
The sickle-cell anaemia is caused by the substitution of glutamic
acid (Glu) by valine (Val) at the sixth position of the beta globin
chain of the haemoglobin molecule. The substitution of amino acid in the
globin protein results due to the single base substitution at the sixth
codon of the beta globin gene from GAG to GUG. The mutant haemoglobin
molecule undergoes polymerisation under low oxygen tension causing the
change in the shape of the RBC from biconcave disc to elongated sickle
like structure.