The sickle form of the hemoglobin gene is created when an adenine nucleotide is changed to a thymine. ... That single amino acid replacement in the -globin protein alters the shape and the chemistry of the hemoglobin molecule, causing it to polymerize and distort the red blood cell into the sickle shape.
Radiometric dating is a kind of technique used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed.