In a yeast plasmid shuffle, you use three different selectable markers in your strain at the time you are screening for the conditional alleles of interest. The first marker is in the chromosome, the second marker is on the plasmid that carries the wild type copy of the gene of interest, the third marker is on the plasmid that could potentially carry the mutant allele of interest.
A. What is the purpose of each of these three markers? What is the purpose of the plasmid that contains the second marker?
B. One of these three markers has to have a special property that is not needed in the other two markers. What is this property, which of the three markers possesses it, and why is this important?