Question

QUESTION 20 In a haploid, a nonsense suppressor su1 acts on mutation 1 but not on mutation 2 or 3 of gene P. An unlinked nonsense suppressor su2 works on P mutation 2 but not on 1 or 3. Explain this pattern of suppression in regard to the nature of the mutations and the suppressors. The mutations are likely frameshift mutations, resulting in three possible proteins. The suppressor mutation may be specifically complementing the protein shape of one mutant but not the others. The mutations are likely nonsense mutations, resulting in three possible stop codons, and the suppressor mutation may be specific to one type of stop codon. The mutations are likely due to one nucleotide deletions in different sections of the gene and this leads to stop codons in three different locations. The suppressor mutations are specific about where they are able to add the missing nucleotide. All of the above are reasonable explanations.

Answer 1

Assuming that the three mutations of gene Pare all nonsense mutations, there are three different possible stop codons that might be the cause (amber, ochre, or opal). A suppressor mutation would be specific to one type of nonsense codon. For example, amber suppressors would suppress amber mutants but not opal or ochre.