Question
The sixth mutant codon of beta globin gene causing polymerization of Haemoglobin and change in RBC shape is
This question was previously asked in
NEET UG Re-Exam 2026 Question Paper (21-Jun-2026)
The correct answer is
GUG
Mutant Codon in Beta Globin Gene Explained
The question concerns a specific mutation in the beta globin gene responsible for altering red blood cell (RBC) shape and causing haemoglobin polymerization. This condition is characteristic of sickle cell anemia.
Identifying the Sickle Cell Mutation
- The mutation occurs at the sixth position of the beta globin protein.
- The normal codon is $GAG$, which codes for the amino acid Glutamic acid.
- The specific mutant codon causing the disease is $GUG$.
- This change replaces Glutamic acid with the amino acid Valine at the sixth position.
- This single amino acid substitution (Glu → Val) alters the haemoglobin molecule (HbS), causing it to polymerize under low oxygen conditions.
- The polymerization distorts the RBCs into a sickle shape, leading to various complications.
Therefore, the sixth mutant codon responsible for these effects is $GUG$.
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