[Campbell Biology P.406] According to Figure 17.26, what is the specific change in the β-glo... | Practice Question

According to Figure 17.26, what is the specific change in the β-globin gene's template strand DNA and the resulting amino acid alteration that leads to sickle-cell disease?

  • A: A change from CTC to GAG on the template strand, leading to Valine (Val) instead of Glutamic acid (Glu).
  • B: A change from GAG to GUG on the template strand, leading to Glutamic acid (Glu) instead of Valine (Val).
  • C: A change from CTC to CAC on the template strand, leading to Valine (Val) instead of Glutamic acid (Glu).
  • D: A change from CAC to CTC on the template strand, leading to Glutamic acid (Glu) instead of Valine (Val).

Explanation

Figure 17.26 clearly illustrates that in sickle-cell disease, the wild-type β-globin DNA template strand's CTC sequence is changed to CAC. This single nucleotide-pair substitution results in the mRNA codon changing from GAG to GUG. Consequently, the amino acid Glutamic acid Glu is replaced by Valine Val , leading to the altered hemoglobin structure characteristic of sickle-cell disease.