lec 4 Flashcards
(18 cards)
quantitative trait locus (QTL)
loci that contribute to quant. traits
QTL - more contributing genes of a specific quant. trait = more probability of developing it
linkage studies
- study large families over several generations
- works well with dominant alleles, mendelian inheritance
gene disease association studies
- statistic relationship between trait and genetic variants between populations
- are certain genetic markers associated with a specific trait
- works well with complex inheritance
4 interpretations for finding an association
- by chance
- result of bias (linkage disequilibrium)
- population stratification, cases and controls selected from genetically different subsets of the population
- genetic variant is causal
linkage studies
advantages and disadvantages
localization of areas across genomes
study many markers at the same time
but it is hard to recruit multigenerational cases and difficult to study complex traits
gene association studies
advantages and disadvantages
good for rare traits
good for testing individual SNPs
good for detecting interactions
but can’t test causality, prone to confounding variables and can be expensive
QTL mapping (what is it, requires and limitations)
- requires: measurable trait, group of genetically related individuals that differ genetically for the trait, genetic markers across genome
- limitations = need large sample size, inbred pops are not representative, correlation does not equal causation
liability threshold
the more QTL that an individual inherits, the higher likelihood will show phenotype
- distribution curve, the further threshold is passed the more severe the phenotype
- QTL contributing to disorder may overlap
charles darwin
natural selection + adaptive radiation, survival of the fittest
- his finches, beak shapes were adapted for diff diets
- adaptive radiation = a single ancestral species gives rise to multiple species through evolution
intra vs intersexual selection
- intrasexual selection - complete with same sex for mates
- intersexual selection - improve attractiveness
fitness and inclusive fitness
fitness - measure of number of offspring someone has
inclusive fitness - favor those genetically related to them → fitness of individual + part of fitness of genetically related individuals
- kin selection
- selfish genes - genes maximize reproduction through inclusive fitness
factors influencing genetic diversity
- inbreeding - inbreeding depression reduced viability of offspring
- gene flow - introduction of new alleles into pop
- mutations in dna
postnatal environmental effects
environmental effects which effect phenotype AFTER birth
- parenting, physical illness, stress, culture
prenatal environmental effects
environmental effects which effect phenotype BEFORE birth
- nutrition, hormones, drugs, maternal stress
congenital adrenal hyperplasia
incomplete male genetalia on XX baby
androgen insensitivity syndrome
XY people fail to develop male specific sex features (fails to bind testosterone) (partial is where genital features are intermediate and complete is where XY people look exactly like XX, but cannot reproduce due to no ovaries)
brain development - medial preoptic area
- area involved in male typical behaviors, is bigger in males as testosterone inhibits apoptosis
- females given high testosterone show more aggression and males who get it cut off stop behaving masculine
exogenous vs endogenous
exogenous factors - fetal alcohol syndrome
endogenous hormones - sex specific traits, bipotential - undifferentiated gonads (will become ovaries or testes depending on hormonal signals)
