Silent cassette Active c assette Silent cassette 17.3 Yeast can switch HML MAT HMR silent and active loci for mating type Frequent Change of mating type occurs when o cassette Figure 17. 5 Changes of ↓ replaces a cassette mating type occur when F nt silent cassettes replace active Change of matin cassettes of opposite occurs when a c replaces ocas sette genotype; when transpositions occur between Rare cassettes of the same type, ■■ No change of mating the mating type remains sette of same type unaltered replaces active cassette 消当Figure 17.5 Changes of mating type occur when silent cassettes replace active cassettes of opposite genotype; when transpositions occur between cassettes of the same type, the mating type remains unaltered. 17.3 Yeast can switch silent and active loci for mating type