A particular DNA mutation produces a UGA stop codon in the middle of the RNA coding for a specific protein. A second mutation in the cell causes a single nucleotide change in a tRNA that enables the correct translation of the protein - meaning, the second mutation suppresses the defect caused by the first. What nucleotide change has most likely occurred in the mutant tRNA molecule and what consequences would the presence of the mutant tRNA have for the translation of the normal genes in this cell?