posted by Anonymous .
Hemoglobin is a critical oxygen-carrying protein. The protein functions as a tetramer with two α-globin subunits and two β-globin subunits. Individuals homozygous for a specific single point mutation in the region that encodes the sixth amino acid in β-globin develop sickle-cell anemia, a disease that causes red blood cells to form a sickle shape. The sickled shape leads to problems with blood flow due to the accumulation of the misshaped hemoglobin. The DNA sequence encoding the fifth, sixth, and seventh amino acids of the normal and mutant β-globin is given.
Normal DNA sequence: 5′-CCTGAGGAG-3′
Mutant DNA sequence: 5′-CCTGTGGAG-3′
A. The point mutation causes an amino acid replacement of (1)___________ by (2)___________ for the sixth amino acid of β-globin.