You perform a cell free translation experiment like Nirenberg and Matthaei. You start with 60% C and 40% A. What relative amount of radiolabeled proline do you expect in the translated polypeptides?

Question

Quizplus · Accepted Answer

Given the nucleotide composition of 60% C and 40% A, the possible codons that can be formed are CCA, CAC, ACC, and AAC. Among these, only CCA codes for proline. Since each nucleotide has an equal chance of being incorporated at any position in the codon, the probability of forming CCA is 0.6 (for C) * 0.6 (for the second C) * 0.4 (for A) = 0.144 or 14.4%. However, since each codon is three nucleotides long and we're considering the entire sequence, the percentage of proline (CCA) codons relative to all possible codons formed from these nucleotides is actually higher. The calculation provided directly does not match the typical approach for determining the frequency of a specific codon in a random polymerization based on nucleotide composition. The correct answer should reflect the probability of incorporating a specific amino acid based on its codon(s) availability and the nucleotide composition, but the explanation provided here mistakenly calculates the probability of a single codon formation without considering the context of the question which implies a translation experiment with a mix of nucleotides leading to polypeptide formation. The correct interpretation should involve understanding how the nucleotide composition influences the codon usage and subsequently the amino acid incorporation, but the direct calculation of 14.4% for proline incorporation does not align with the provided options or the expected outcome of such an experiment.

You Perform a Cell Free Translation Experiment Like Nirenberg and Matthaei