A polyribonucleotide prepared from the tetranucleotide AUAC, when subjected to peptide synthesizing conditions, gave the polypeptide Ile-His-Thr-Tyr.A codon for Threonine (Thr) must be

Question

Quizplus · Accepted Answer

The codon for Threonine (Thr) is ACA. Codons are read in the mRNA 5' to 3' direction, and the tetranucleotide sequence AUAC would be read in the same direction for mRNA. Since the polypeptide sequence is Ile-His-Thr-Tyr, and we know the codons for Isoleucine (Ile) can start with A, for Histidine (His) it can start with C (in this context, considering the given sequence and the amino acids produced), and for Tyrosine (Tyr) it ends with UAC, the remaining codon ACA is the only one that fits for Threonine (Thr).

A Polyribonucleotide Prepared from the Tetranucleotide AUAC, When Subjected to Peptide