Question 9 [10 marks / 10 minutes]
Suppose there are two different mutant alleles of the same gene.Sequence analysis shows that both alleles are single nucleotidesubstitutions, and that different nucleotide positions within thegene are affected in each allele. Phenotypic analysis shows thatone allele is a null allele, and the other is dominant negative(antimorphic).
Explain what this information reveals about the two mutations. Givea hypothesis for how these two mutant alleles could show suchmarkedly different effects. [10 marks]
