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Unformatted text preview: ains, switching occurs at a much higher
frequency than one would expect if the switch were due to a
point mutation. The homothallic phenotype arises from a
dominant, functional HO allele at the HO locus on chromosome IV; by comparison, heterothallism results from a recessive loss-of-function allele (ho) at this same locus. (a) 1n
(Diploid) MATa /
(Haploid) Mating MATa MATa 1n
(Haploid) MATα Storage locus
HMLα CEN MATα α2 MATa Ya
Telomere α-specific genes
No transcription HMLα
Yα a-specific genes Figure A.11 (b) In an a cell
Transposition Transcription Mcm1 Repressors MATa Telomere Mcm1 ActIvators MATα Cassette playback
α1 MATα Switching
of mating type (b) (a) In an α cell MATα MATa a-specific genes Figure A.10 Mcm1 protein is both a positive and a negative
regulator. (a) In an cell, Mcm 1 acts together with 1 to activate
transcription of -speciﬁc genes but acts with 2...
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This note was uploaded on 10/03/2013 for the course BI 206 taught by Professor Celenza during the Spring '08 term at BU.
- Spring '08