Yeast Signal Transduction Lab Saccharomyces cerevisiae

Yeast are… Eukaryotes Single celled organisms Kingdom Fungi Commonly used in biological experiments Also used in commercial applications such as bread and wine preparation

Fungi vs. Bacteria FUNGIBACTERIA Eukaryote Unicellular or Multicellular Cell Wall Never photosynthetic Prokaryote Always Unicellular Cell Wall Can be photosynthetic

Haploid Strains of Yeast MAT a –Release “a factor” pheromones –Have receptors for  factor MAT  –Release  factor pheromones –Have receptors for “a factor”

Yeast Mating When the appropriate factors are released, a MAT  and MAT a cell can mate The binding of the pheromone to the receptor causes a signal transduction pathway to be activated. Cells start to grow towards one another– they shmoo!

Diploid vs. Haploid What are the advantages of being diploid? –2 copies of every gene –Allows you to compensate for a “bad” gene

Growth of Yeast YED media –Complete media –Any yeast should be able to grow on it. MV media –Minimal media –Lacks some nutrients that yeast might need –If a yeast cell can’t make these nutrients themselves, they can’t grow on MV media

Yeast mutants Some yeast contain mutations that do not allow them to produce specific compounds = auxotrophic When a yeast mutant is auxotrophic for a specific compound, it will be unable to grow on MV media.

Yeast mutants (continued) In order for an auxotrophic yeast to grow –The compound has to be added to the media OR –The yeast must mate with another yeast strain that can complement it (so it can make the compound) = complementation

Lab Experiment Week 1: Mate haploid yeast and observe growth on MV media (to show complementation), observe shmooing Week 2: Determine the defect in haploid yeast strains through mating and complementation on MV media

Your homework: Study for the Pre Lab Quiz Set up lab notebook: –Write a SPECIFIC title –Write an Intro (2-5 sentences) –Paste in procedure –Make a flowchart for EACH page of the procedure