Sex Linkage and Extranuclear Inheritance Lab

Simplifications: flies are drawn from top view and bred one offspring at a time with fair Mendelian chances. Later generations mate random F1 (or F2) females with random F1 (or F2) males; exceptional XXY and XO flies are counted but not used as parents. Nondisjunction is shown only in the mother and is exaggerated to 1 in 20 eggs (real primary nondisjunction is about 1 in 2,000). The sex-influenced stripe gene and the mito type marker are teaching models. Maternal effect embryos are scored before hatching, and headless embryos do not survive to breed.

Problems are randomly generated. Type probabilities as a fraction (1/8), a decimal (0.125) or a percent (12.5%). Families are fictional. Assume full penetrance, no new mutations and, for mtDNA, no paternal transmission. Inheritance-mode data are random samples, so ratios are close to, not exactly, the expected values.