Saccharomyces_A

Saccharomyces_A - har06584_refA_001-020 17:23pm Page 1...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Saccharomyces cerevisiae, commonly known as baker’s yeast, has been a preferred organism for genetic research since the mid–twentieth century ( Fig. A.1 ). The experimental value of this single-celled eukaryotic species lies in its simple life cycle, alternating haploid and diploid phases, short generation time, and easy-to-identify meiotic products. Recent techno- logical advances enable yeast biologists to use genetic analy- sis to gain a deep understanding of the organization and regulation of eukaryotic cells. Like all eukaryotic cells, yeast cells make decisions that determine their fate. They decide, for example, whether they are a or cells, and whether to mate, enter the meiotic path- way, grow and divide by mitosis, or bud. Researchers can use genetic techniques to analyze the molecular events that influ- ence these fate-determining decisions; and knowledge of these events, which include the activation and inactivation of transcription factors, can contribute to an understanding of how the cells of multicellular organisms differentiate. Three main themes unify our genetic portrait of yeast. First, to identify the genes and proteins influencing develop- ment, researchers isolate and study mutants defective for a specific process. Second, master regulatory genes in yeast control the expression of other genes, whose activ- ities determine the phenotype of a cell. Third, cascades of proteins called signal transduction systems (described in Chapter 19 of the main textbook) transmit the signals responsible for shifting a cell from one phenotype to another. In examining yeast as a model organism for understanding development, we present: An overview of yeast in the laboratory: significant details of the yeast life cycle, current knowledge of the yeast genome, and basic tools for looking at yeast. Cell differentiation: molecular mechanisms for determining cell type. Mating: how cell-to-cell communication through pheromones promotes the conversion of haploid cells to diploid cells. Yeast colonies, each containing about 10 7 cells, grow from single cells spread on solid media. Saccharomyces cerevisiae: Genetic Portrait of a Yeast Reference A A.1 An Overview of Yeast in the Laboratory Yeast geneticists have gathered enough information on S. cerevisiae to state with confidence that single-celled eukaryotes such as yeast express genes, organize themselves, perform biological functions, and differentiate using varia- tions of the same processes found in multicellular eukaryotes. Yeast has proven to be an excellent model for the study of cell cycle control and for the dissection of eukaryotic signal transduction pathways. Using standard genetic analyses and newly developed genomic tools, yeast re- searchers continue to provide critical insights into basic cellular processes.
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
The Yeast Life Cycle Yeast cells alternate between haploid (1 n ) and diploid (2 n ) phases in which new daughter cells arise mitotically as buds that grow in size and eventually split from the mother cell ( Fig. A.2 ). Haploid cells occur in two mating types,
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern