Which of the following amino acid substitution is responsible for causing sickle cell anemia?

Options

A. Valine is substituted by Glutamic acid in the `alpha`-globin chain at the sixth position
B. Valine is substituted by Glutamic acid in the `beta`-globin chain at seventh position
C. Glutamic acid is substituted by Valine in the `alpha`-globin chain at the sixth position
D. Glutamic acid is substituted by Valine in the `beta`-globin chain at the sixth position

Answer

D

Explanation

The Sickle cell anaemia results from the substitution of Glutamic acid (Glu) by Valine (Val) at the sixth position of the `beta`-globin chain of the haemoglobin molecule.
Single base substitution at the sixth codon of the B-globin gene from GAG to GUG is responsible for the substitution of amino acid in the globin protein (point mutation).