An important validation of the genetic code occurred when George Streisinger determined the amino acid sequence of bacteriophage T4 lysozyme and of mutants induced by proflavin, a dye with a planar structure that can intercalate (fit) between successive base pairs in DNA and induce Trameshif mutations-that is, mutations involving additions or deletions of a single base. Streisinger and colleagues found that a particular single-base insertion mutation could be suppressed, with wild-type function restored, by a mutation that evidently involved a single-base deletion at a nearby site. Shown below are portions of the amino acid sequence of wild-type T4 lysozyme and the putative double mutant. Te remaining parts of the sequence were unchanged. Identify mRNA sequences that could encode each of these amino acid sequences and deter-mine whether your codon assignments are consistent with the genetic code.
Wild-type ... Lys - Ser - Pro - Ser - Leu - Asn - Ala ...
Double mutant ... Lys - Val - His - His - Leu - Met - Ala ...