Correct Answer: B
Explanation:
tRNA, which contains 3 anti-codon bases for every amino acid it carries, matches up opposite the mRNA codons that are also three bases long. This means that the mRNA in question potentially codes for 429/3 amino acids. This gives us a potential of 143 amino acids or choice (A). However, the stop sequence does not code for an amino acid, so this gives us 142 amino acids coded for. Care should be exercised when considering the start sequence. While not a part of the resulting protein, that site does code for the amino acid methionine in the translation process.