COMEDK 2007 MCQ Answer 130

The correct answer is B

Point mutations = change of single nucleotide in the DNA.

Single nucleotide changes (point mutations) in the sequence of a gene can result in changes in the amino acid sequence of a protein produced from the mutated gene. One of the most well studied examples of the effects of a mutation on the sequence of a protein involves the oxygen-transporting protein hemoglobin. A point mutation creates an altered form of hemoglobin that produces the genetic disorder called sickle-cell disease (sickle-cell anemia).

Sickle-cell disease results from a point mutation in the second nucleotide of the codon GAA, which results in a change in the amino acid at position 6 in the hemoglobin protein.