Final answer:
The messenger RNA for a 5-amino acid bacterial protein must contain at least 15 nucleotides due to the triplet code, with each amino acid being specified by three nucleotides.
Step-by-step explanation:
If a bacterial protein contains 5 amino acids, the messenger RNA that would direct its manufacture would have at least 15 nucleotides. This is because an mRNA molecule uses a triplet code to specify each amino acid, which means every amino acid is encoded by a sequence of three nucleotides. Therefore, for a protein with 5 amino acids, the sequence would be 5 amino acids multiplied by 3 nucleotides per amino acid, equaling a minimum of 15 nucleotides needed in the mRNA sequence.