Instruction
The image below shows the schematics illustrating the concepts of incomplete penetrance and variable expressivity and includes the P = G + E + (GxE) formula that we discussed in class a few days ago.
Image showing examples of incomplete penetrance and variable expressivity
This formula says that every phenotype is the sum of genotype, the environment and whatever interactions there may be between genotype and environment. For example, sometimes hair color can be dictated by certain genes (G), by dying it with a color of your choice (E) and by a combination of your genes and the environment, for instance when your hair color changes based on sun exposure or diet (and everything in between!!)
In this assignment, I'm asking you to discuss (in 200 words or fewer) which components in the P = G + E + (GxE) formula may help us explain the concepts of incomplete penetrance and variable expressivity. To guide you in your reasoning, think about the following question: If we know that a dominant allele A makes flowers purple, what could explain that some Aa individuals are not purple at all (incomplete penetrance), or they show a much less intense purple coloration (broad expressivity)?