Suppose that prior to mating-type switching in a haploid yeast cell, MAT is expressed in the active locus. During mating-type switching by homologous recombination

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During mating-type switching in yeast, the MAT genes in the active locus are not simply switched places with or moved around. Instead, the information from a silent donor locus (either HMRa or HMLα, depending on the cell's current mating type and the switch direction) is copied and used to replace the MAT genes in the active locus through a process involving homologous recombination. This effectively changes the cell's mating type. The original MAT genes are degraded and replaced, not physically moved or swapped.

Suppose That Prior to Mating-Type Switching in a Haploid Yeast