A particular human polypeptide is 137 amino acids long. How long (in nucleotides) is the open reading frame? An mRNA encodes a polypeptide that is 312 amino acids in length. a. How many sense codons does this mRNA contain? b. How many nonsense codons does this mRNA contain? c. The 53^rd codon of this mRNA normally codes for the amino acid tryptophan (Trp). Suppose a mutation occurred in the gene that changes this Trp codon into a stop codon. How many amino acids would be in the resulting polypeptide? For each of the following statements, indicate whether it applies to protein synthesis in prokaryotes, eukaryotes, both, or neither. a. AUG is the start codon. b. The mRNA has a ribosome-binding site. c. The mRNA is translated in a 3′ rightarrow 5′ direction. d. The enzyme that catalyzes peptide bond formation is an RNA molecule.