Sickle-cell anaemia is an autosome linked recessive trait. At the molecular level, this disorder is caused by a single base substitution at the sixth codon of the -globin gene. Which of the following represents the correct change in the mRNA codon?

Step-by-step solution

Sickle-cell anaemia is caused by a point mutation at the sixth position of the -globin chain of the haemoglobin molecule. The mutation involves a single base substitution in the DNA, where the CTC codon on the template strand is changed to CAC. This results in a change in the mRNA codon from GAG to GUG. Consequently, the amino acid glutamic acid (Glu) is replaced by valine (Val) at the sixth position of the -globin chain. Therefore, the correct change in the mRNA codon is GAG GUG. Answer: GAG GUG