quiz epigenetics and genetics: look over calculations for odds ratios and lod ratios, quantitative genetics calculations. all start with same types of cells, stem cells, containing same amount of genes, genes regulated by other factors and proteins within genome. model organisms used to study development: zebrafish, nematode c elegans, arabidopsis, mouse, fruit flies, used to. Look at flies and mice to drive development in humans: pathways and genetic mechanisms conserved, what occurs in flies, occur in humans, genomes sequenced so can find genes with mutant phenotypes. Loss of function of eyeless gene in drosophila = > no eye or small eye forming. mutations: no functional copies of aniridia eyes embryos have no eye formation, lethality in utero. homozygous loss of function leads to embryonic lethality: heterozygote lack one or two irises. Forward genetics mutagenize model organisms: cross mu tant mice with wildtype mice to perform phenotypic analysis.