Deletion, substation, or addition that alters the sequence of the stop codon would have what structural effect?

Deletion, substitution or addition cause mutation that alters the sequence of the stop codon. These can lead to change the structure of the codon. If a stop codon is altered to any other codon, the codon will start coding for that amino acid and the synthesis of polypeptide continues and some another protein is formed in the place of original polypeptide.