Q. A haploid strain of Aspergillus nidulans carried an auxotrophic met-8 mutation conferring a requirement for methionine. Several million asexual spores were placed on minimal medium, and two prototrophic colonies grew and were isolated. These prototrophs were crossed sexually with two diverse strains, with the progeny, where met+ means that methionine is not necessary for growth and met- means that methionine is required for growth.
Crossed with: Prototroph 1:
Prototroph 2:
a) describe origin of both of the original prototrophic colonies.
b) Elucidate results of all four crosses, using clearly defined gene symbols.