COMPLEX TRAITS Flashcards
what controls complex traits
: Complex traits are governed by a combination of multiple loci and environmental factors, not following simple Mendelian inheritance rules.
what is genetic determinism
Genetic determinism is the idea that genes solely determine physical characteristics or behaviors, rather than a combination of genetic and environmental factors.
What is an example of how genetic determinism is incorrect?
An example is the colorpoint locus in cats, where enzymes for coat pigmentation are temperature-sensitive, showing that environmental factors (temperature) influence phenotype.
PENETRANCE
Penetrance is the proportion of individuals with a given genotype that show the expected phenotype
EXPRESSIVITY
Expressivity is the degree to which a gene is expressed, which can be influenced by both internal and external environmental factors.
What is the difference between additive and non-additive gene action?
Additive gene action refers to effects where genes contribute equally to the phenotype, while non-additive gene action involves interactions like dominance and epistasis.
What is broad sense heritability?
Broad sense heritability is the proportion of phenotypic variation in a population that is due to genetic variation (including all genetic factors).
What is narrow sense heritability?
Narrow sense heritability is the proportion of phenotypic variation that is due to additive genetic variance, which is more useful for predicting response to selection.
What does QTL mapping involve
QTL mapping involves crossing two lines that differ in traits, correlating the phenotype to genetic markers in the offspring, and identifying markers that segregate with the trait of interest.
How is GWAS different from QTL mapping?
GWAS is used for natural populations without the need for controlled crosses, assessing many alleles at once to identify genomic regions associated with traits.
What is linkage disequilibrium?
Linkage disequilibrium refers to the degree to which one genetic variant is inherited or correlated with a nearby genetic variant in a population.
What is the consequence of eugenics based on genetic determinism?
Eugenics is a flawed concept where certain groups are prevented from reproducing to create a “fitter” population, wrongly assuming that all human traits are solely controlled by genetics.
What does heritability measure in genetics?
Heritability estimates how much of the variation in a trait is due to genetic differences, helping to distinguish genetic from environmental influences.
In complex traits, what increases the risk of developing a trait?
Having specific genetic variants increases the risk of developing a trait, but it is not a certainty.
What are the different APOE gene variations associated with Alzheimer’s disease (AD)?
E3: No specific association
E2: Reduced risk
E4: Higher risk
Additive effect: Having two copies of E4 increases risk more than having one.
