Screens or selections
Look for phenotype results from the alteration of gene activity.
Phenotypes can differ in different situations
Why do this?
Demonstration of random mutations: The Luria/Delbrück Experiment (1943)
Characterizing putative mutants by whether they breed true.
Only some of the progeny will have the mutant phenotype.
Dominantly-acting alleles in a heterozygote
Penetrance and expressivity.
All animals have the same mutant phenotype.
Independent assortment of traits
With two genes one expects Mendelian ratios of 9:3:3:1
Some mutations can give altered ratios
Approaches to Genetics problems (in handout)