Question

A haploid "a" Δade4 strain of yeast is mated to a haploid ¨α¨ Δade2 strain of yeast. What is the phenotype of the resulting diploid in terms of minimal growth on minimal media and color of YPD?

Answer 1

ade4 and ade2 genes are involved in the adenine biosynthesis pathway. ade4 mutation, as well as ade2 mutation, will lead to a halt in adenine biosynthesis.This results in the accumulation of the previous gene products (which are pink in color) and the ade4 mutant, as well as adae2 mutants, will have pink colonies in media that lack adenine. The resulting diploid of this mating will heterozygous for ade4 and ade2 which means it has a copy of functional ade2 allele and mutated ade2 allele, and a functional ade4 allele and mutant ade4 allele. since functional gene products of ade2 and ade4 are present they complement each other and there will be a proper adenine biosynthesis. so the diploid will have white colonies (the resulting phenotype of the diploid) and the color of YPD will be its normal color.