In sickle cell anaemia glutamic acid is replaced by valine Which one of the following triplets codes for valine ?

Options

A. GGG
B. AAG
C. GAA
D. GUG

Answer

D

Explanation

Sickle-cell anaemia is a recessive autosomal gene disorder. This disease is controlled by a single pair of allele HbA and Hbs. It is caused due to inheritance of a defective allele coding for beta globulin. It results in the transformation of HbA into HbS in which glutamic acid (Glu) is replaced by valine (Val) at sixth position in each of two beta chains of haemoglobin. This substitution occurs due to the single base substitution of the beta globin gene from GAG (Glu) to GUG (Val). Whereas, the other codes GGG, AAG. GAA do not codes for valine.