The original mRNA sequence is GUU (valine), and with the substitution mutation changing the last base to Cytosine, the new codon becomes GUC, which also codes for valine. Since the amino acid remains the same, there is no phenotypic change, as the resulting protein will be unaffected by this silent mutation.
Consider an mRNA strand that has a sequence of base pairs of GUU CUA ACU. Suppose a substitution mutation occurred in the DNA, resulting in the last base in the first codon of the mRNA to be replaced by Cytosine. Using the codon chart below, a) identify which amino acid will now be formed, b) identify whether or not there will be a phenotypic change, and a brief explanation. Your answer should be in 2-4 sentences.
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