Haploid cells occur in a and mating types that

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Unformatted text preview: r eukaryotic organisms as we examine the simple, multicellular plant known as Arabidopsis. Essential Concepts 1. During the yeast life cycle, cells alternate between haploid and diploid phases. Haploid cells occur in a and mating types that communicate with each other via pheromones; the fusion of cells of opposite mating types creates diploid zygotes. 2. The nuclear genome of yeast contains 16 linear chromosomes carrying about 6000–6500 genes; very few of these genes have introns. The yeast genome also contains few repeated sequences. 3. Yeast geneticists use genetic crosses, mutant isolations, transformation studies, and gene replacement to answer questions about eukaryotic cell functions that are difficult to answer with other organisms. 4. Genes at the MAT locus act at the level of transcription to control the expression of other genes that determine cell type. MAT consists of two genes: 1 and 2. 1 encodes an activator of -specific genes encoding proteins that elicit the -type cell. 2 encodes a repressor of a-specific functions. A simple network...
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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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