Question
Biology Question on Principles of Inheritance and Variation
Replacement of which one of the following nucleotides in the Hbb gene causes sickle cell anaemia ?
A
A to T
B
A to U
C
U to A
D
C to G
Answer
A to U
Explanation
Solution
The mutation causing sickle cell anemia is a single nucleotide substitution (A to T) in the codon for amino acid 6. The change converts a glutamic acid codon (GAG) to a valine codon (GTG). The form of hemoglobin in persons with sickle cell anemia is referred to as HbS.