1. **Stating the problem:** We are given DNA codons for amino acids and some mutations. We need to determine which mutations change the amino acid sequence of a protein. 2. **Understanding codons and mutations:** Each codon (a sequence of three DNA bases) codes for a specific amino acid. A mutation changes one codon to another. If the new codon codes for a different amino acid, the mutation changes the amino acid sequence (a nonsynonymous mutation). If it codes for the same amino acid, the mutation is silent (synonymous). 3. **Given codons and amino acids:** - Ala: CGA, CGG, CGC - Arg: GCA, GCG, GCT - His: GTA, GTG - Iso: TAA, TAG, TAT - Leu: AAT, AAC, GAA - Met (start codon): TAC - Thr: TGA, TGG, TGT - Tyr: ATA, ATG 4. **Analyze each mutation:** - Mutation 1: AAT mutated to GAA - AAT codes for Leu - GAA codes for Leu - No change in amino acid - Mutation 2: GTA mutated to GTG - GTA codes for His - GTG codes for His - No change in amino acid - Mutation 3: TAA mutated to AAT - TAA codes for Iso - AAT codes for Leu - Change in amino acid - Mutation 4: ATA mutated to ATG - ATA codes for Tyr - ATG codes for Tyr - No change in amino acid 5. **Conclusion:** Only the mutation from TAA to AAT changes the amino acid sequence of the protein. **Final answer:** The mutation TAA to AAT changes the amino acid sequence.