Chapter 10, Problem 8P

Wild $\text{-}$ type β $\text{-}$ globin protein is composed of $\text{146}$ amino acids. A β $\text{-}$ globin gene mutant known as Hb Cranston contains $\text{157}$ amino acids. Partial mRNA sequences of ${\text{β}}^{\text{A}}$ and Hb Cranston ( ${\text{β}}^{\text{Cr}}$) are shown. The numbers indicate amino acid positions. Identify the mutation that causes ${\text{β}}^{\text{Cr}}$, and describe how the mutation leads to a longer than normal β $\text{-}$ globin protein chain.