Saccharomyces_A

Meiosis reduces the diploid nucleus to four haploid

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Unformatted text preview: ironment at hand. Meiosis reduces the diploid nucleus to four haploid nuclei, which become encapsulated in four haploid spores. On the addition of nutrients, the haploid cells bud and can divide mitotically. Yeast populations must experience an alternation of feast and famine to complete the life cycle. Nutrient depletion induces meoisis and sporulation, while the subsequent availability of nutrients promotes spore germination and gamete production. The association of haploid and diploid phases with periodic fluctuations in environmental conditions is common among eukaryotic microorganisms. Sex in yeast is determined by the mating type locus (designated as MAT) on chromosome III. As already mentioned, there are two mating types: a and a. Mating ability segregates 2a : 2 in tetrads derived from MATa/MAT heterozygous diploids, indicating that the a and a mating types are specified by alleles of a single locus (MAT). MATa or MAT cells mate efficiently with cells of the opposite sex. Heterozygous MATa/MATa diploids are sterile, but it is possible to derive MATa/MATa o...
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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.

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