Mutations can occur at several locations on a gene yet result in the same phenotype. Yeast are a good organism to study the heritability of mutations because of their small size, easy and quick growth, and easily definable phenotypes. These factors also make yeast good for using tetrad analysis to determine genotypes. To study this, several crosses were carried out on adenine deficient agar plates to see what haploid gametes and what diploid cells could survive without adenine present. It was found that HA0 is the only haploid yeast cell that can grow without adenine, while HA1, HA2, and HB1 cannot grow without adenine. HB1xHA0 and HB1xHA2 were able to grow without adenine present, while HB1xHA1 and HA1xHA2 were unable to grow without adenine present. These results occurred because of the locations of the mutations on the gene, resulting in dominant alleles, mutation matches, complementation, and non-mating. A tetrad analysis was then taken of HB1xHA2. The results of the analysis show that there is a roughly 1PD:4TT, with three unknown tetrads due to culture deaths. While the analysis showed the correct ratio of PD:TT, it cannot be confirmed if the genes are linked or not due to the undefined tetrads.
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