Sickle-cell disease is caused by a so-called point mutation in the human -globin gene. A point

Question:

Sickle-cell disease is caused by a so-called point mutation in the human β -globin gene. A point mutation is the result of a single base substitution in the DNA encoding a gene. The sickle-cell mutation results in the substitution of Val for Glu at position 6 in the b β -globin protein.
a. Using the information in Figure 5.17, explain how a point mutation could change a codon for Glu to a codon for Val.
b. Do you expect the pI for the sickle-cell β -globin to be higher or lower than the pI for wild-type β -globin? Explain.