Yeast

The YED plate and the MV+Adenine plate do not provide information directly about whether the mutation in the yeast is Ade1 or Ade2, rather, they act as different forms of a control. The YED plate contains all the nutrients needed by the yeast to grow, but has a suboptimal amount of adenine. Because of this, the yeast cells attempt to synthesize adenine, and the mutants that build up AIR turn red. On the other hand, the colonies of yeast which are wild type or which complement each other are able to produce adenine with no buildup, and remain white (Figure 4). The appearance of red cells on this plate is a confirmation that some of the mating crosses did not have complementary genes.