The eyes of Drosophila develop from imaginal discs, groups of cells set aside in the fly embryo that differentiate into the adult structures during the pupal stage. Despite their importance in nature, eyes are dispensable for fruit-fly life in the laboratory.

Part A

Devise a genetic screen to identify genes directing development of the fly eye Drag the terms on the left to the appropriate blanks on the right to complete the sentences. Terms can be used once, more than once, or not at all.

homozygous heterozygous curly straight dark light Reset Help Male flies for dark body (db) are fed EMS to induce mutations and then mated to females for a balancer chromosome 3 containing the db allele and the dominant marker CyO. Individual F males that have bodies are wings and selected and mated back to a female from the chromosome 3 balancer strain to create many independent F lines. F2 progeny with wings and bodies will be heterozygous for the new mutations. Interbreeding the F2 will create many independent F3 populations. The straight-winged flies within each population will be recessive for new mutations on chromosome 3, and the rest will be for the mutation. F3 that have winged flies with eye abnormalities identify fly lines with mutations on chromosome 3 affecting eye development.