Gene X Flashcards
What would you say about the following graph?
With low environmental exposure, all 3 genotypes are phenotypically equivalent. However, as the environment is changed such that environmental stressors increase, the 3 genotypes produce different phenotypes. Thus, environmental interaction is necessary with genotype to produce the phenotype.
Explain why this image shows no interaction between genes and environment.
In the top example, individuals with either genotype do not see any change in phenotype with a change in environment. Thus, that environmental change did not interact with their genotypes.
In the bottom example, we see that genotype certainly affects phenotype becuase genotype 1 and 2 do not start with the same level of phenotype. However, as the environment is changed they both experience the same decline in phenotype. Thus, the change in environment is not interacting with their genomes because it decreases their phenotype regardless of genotype.
Explain why this image shows interaction.
In the top image, genotypes 1 and 2 start off with the same phenotype. However, as the environment is changed, individuals with genotype 1 remain resilient and thos with 2 display a decreased phenotype. Thus, the environment is interacting with the genome because individuals with different genotypes are impacted differently.
In the bottom iamge, genotypes 1 and 2 start off with a clear impact of differing genotype on phenotype. However, as their environments are changed genotype 1 shows a decrease in phenotype and genotype 2 shows an increase in phenotype. Thus, the environment is interacting with the genome because individuals with different genotypes are impacted differently.
What is the differential susceptibility/plasticity model?
A model for gene x environmental interactions that says that such interactions can confer either a negative (vulnerable) or positive (resilient) outcome depending on the environment. This is referred to as plasticity.
Explain the difference between these 2 figures.
The larger image shows the differential susceptibility model, where individuals can show positive or negative outcome (plasticity) based on the interactions between their genome and the environment. A “fixed individual” is a resilient person who does not vary in the different environments. The smaller image shows the diathesis - stress model, where by a person whose genome is affected by interaction with the environment will only show an increase in outcome until the reach the level of a person who is “resilient” or unaffected by the environment. This does not acount for the fact that some people can do better that the resilient individual in the right conditions.
Explain how this image shows gene dosing.
Gene dosing occurs when an individual’s phenotype depends on the number of alleles they have of a specific kind (i.e. homozygous WT, heterozygous, or homozygous mutant). In this image, a person who has 1 or 2 T alleles shows a greater change in phenotypic outcome than a person who has no T alleles.
