Refer to Table 13.1. Can you hypothesize why a synthetic RNA composed of a mixture of poly U  poly A would not stimulate incorporation of ¹⁴C-phenylalanine into protein?

Key Concepts

Role of mRNA in Protein Synthesis

Messenger RNA (mRNA) serves as the template for protein synthesis, carrying genetic information from DNA to ribosomes. It is composed of codons, which are sequences of three nucleotides that correspond to specific amino acids. For protein synthesis to occur, the mRNA must contain the correct sequence of codons that match the amino acids being incorporated into the growing polypeptide chain.

Codon-Amino Acid Relationship

Each codon in mRNA corresponds to a specific amino acid, as defined by the genetic code. For example, the codon UUU codes for phenylalanine. A synthetic RNA composed solely of poly U (which would produce only the codon UUU) and poly A (which does not code for any amino acid) would not provide the necessary variety of codons to stimulate the incorporation of phenylalanine into proteins effectively.

Importance of tRNA in Translation

Transfer RNA (tRNA) is crucial for translating the mRNA sequence into a polypeptide chain. Each tRNA molecule carries a specific amino acid and has an anticodon that pairs with the corresponding codon on the mRNA. If the synthetic RNA lacks the necessary codons to match with tRNA molecules that carry phenylalanine, the incorporation of this amino acid into the protein will not occur.