GENETICS AND EVOLUTION
INHERITANCE AND VARIATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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GAA
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GAG
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GUA
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GUG
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Detailed explanation-1: -So, the correct answer is ‘GUG’.
Detailed explanation-2: -Valine is coded by four different combinations: GTT, GTC, GTA and GTG.
Detailed explanation-3: -Sickle cell anemia results from the single amino acid substitution of valine for glutamic acid in the beta-chain owing to a nucleotide defect that causes the production of abnormal beta-chains in hemoglobin S.
Detailed explanation-4: -In sickle cell anaemia, base substitution from glutamic acid to valine occurs at the relevant portion of the beta chain of the haemoglobin molecule. This substitution occurs due to the single base substitution at the sixth codon of the beta globin gene from GAG to GUG.
Detailed explanation-5: -In a person diagnosed with sickle cell anaemia, a point mutation occurs in the beta globin chain of haemoglobin. The gene mutation is a single nucleotide of the -globin gene, which results in glutamic acid substituted by valine at position 6. GAG codon coding for Glutamic acid changes to GUG codon for Valine.