Final answer:
The methionine codon AUG is located at the 5' end of the mRNA, where the ribosome begins translation. This start codon sets the reading frame for translation and signifies the initiation of the protein synthesis process.
Step-by-step explanation:
The codon for methionine (AUG), which is the amino acid located at the amino terminus of a specific protein, would be found closest to the 5' end of the corresponding mRNA. The translation process of mRNA begins at the 5' end, and the ribosome moves along the mRNA molecule from the 5' to the 3' end. The AUG codon not only codes for methionine but also signifies the initiation of translation, thus setting the reading frame of the mRNA.
In the given example of mRNA sequence 5'-AUGCCACGAGUUGAC-3', the sequence starts with the codon AUG which codes for methionine, indicating that this is the first codon of the mRNA and will be the start of the polypeptide chain, with further amino acids added sequentially according to the codons that follow.