Yeast phenotypes

As the results state, HA0 is the only haploid yeast cell that can grow without adenine, while HA1, HA2, and HB1 cannot grow without adenine. This shows that HA0 can synthesize its own adenine, while HA1, HA2, and HB1 have mutations which halt adenine production by the yeast cell, though it is unknown where these mutations are in the genome.