The gene for the beta chain of normal human hemoglobin has the sequence ctc at the position for the seventh amino acid in the protein. a point mutation changing the sequence to cac results in sickle cell hemoglobin. use the genetic code to determine the change in the amino acid at position seven of the hemoglobin beta chain. see section 6.7

I believe the appropriate answer is Glutamic acid to valine. Sickle cell disease is a blood condition prevalent in people of African and  in the tribal people of India. The sickle cell mutation reflects a single change in the amino acid building blocks of oxygen transport protein (hemoglobin). This protein has two sub units the (alpha and beta sub unit), In people with sickle cell the alpha sub-unit is normal. However the beta sub unit has the amino acid Valine at position six instead of the glutamic acid that is present in normal cases