Question

12) A particular allele of a gene (including the wild-type allele) can be expressed in a dominant fashion for several reasons A) Explain why wild-type alleles are usually dominant to mutant alleles (5 pts.). 20 B) Describe three ways in which mutant alleles can be dominant to a wild-type allele (6 pts.).

Answer 1

A)In this case, remember that mutant alleles are product of point mutations that are able to change the expression of a determined gene. These mutations are not normal. However, they can be inherited, increasing their frequency in a population. However, wild type traits are dominant because they are expressed in a much higher frequency and the presence of only one wild allele can mask the presence of the mutant alleles (in most of the cases mutant alleles are recessive with respect the wild type allele)

B)The first scenario would be that the mutant allele confer an advantage to those individuals that express it on their environment. Other scenario is that a phenomenon of sexual selection occurs, where one sex decides to mate with the individuals that posses a particular trait (mostly advantageous trait). Finally, a natural disaster could occur, affecting mostly the wild type population and the mutant individuals posses an advantageous trait that allows them to survive and reproduce.