7. Two missense mutations in the gene that encodes an enzyme called superoxide dismutase cause amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease). This disorder causes loss of neurological function over a 5-year period. One mutation alters the amino acid asparagine (Asn) to lysine (Lys). The other changes an isoleucine (Ille) to a threonine (Thr). List the codons involved and describe how single-base mutations alter the amino acids they specify.