Final answer:
To convert Valine (Val) to Phenylalanine (Phe) on the protein level, a mutation on the template DNA strand from GTT to TTT is required, which will result in the mRNA codon for Phenylalanine (AAA) during transcription. The correct option is B.
Step-by-step explanation:
The question presented requires an understanding of DNA mutations and their impact on protein synthesis. The conversion of the amino acid Valine (Val) to Phenylalanine (Phe) due to a change in the template DNA strand involves changing the codon that corresponds to Valine into a codon for Phenylalanine.
To answer this question, we need to consider the complementary DNA sequence and the resulting messenger RNA (mRNA) that would be transcribed from the mutated template strand. Valine is encoded by the codons GTT, GTC, GTA, and GTG. Phenylalanine is encoded by the codons TTT and TTC. Therefore, converting Val to Phe involves changing a G nucleotide to a T on the opposite, coding strand (remembering to account for the fact that DNA is double-stranded and antiparallel).
Hence, looking at the options, the mutation that would lead from Val to Phe is changing GTT to TTT, because when using the original strand as a template, it would transcribe an mRNA with the codon AAA, which codes for Phenylalanine. So, the correct choice is b) GTT to TTT.