Chapter 14 Gene Control in Development Thu Fenno

Pheromone-Stimulated Gene Expression Upon completion of this lesson the students will be able to: Identify Yeast (Review) Identify Cell Types in Yeast Identify Regulating Pheromone

Yeast (Review) Unicellular Eukaryote Divides by budding Exist as haploid or diploid cells Undergo aerobic or anaerobic respiration Saccharomyces cerevisiae

Morphology of Yeast Cell Type

Cell Types in S. cerevisiae

Pheromone-Stimulated Gene Expression Haploid yeast cells produce pheromones and pheromone receptors

Eukaryotic Cell Cycle

Conclusion S. cerevisiae expresses three different cell types: the two haploid cell types (a and a cells), and the diploid a/a cells. Haploid cells produce pheromones and pheromone receptors. Binding of the pheromones to their receptors on cells of the opposite type leads to gene activation and arrest in the G1 phase of the cell cycle. Fusion of the haploid cells form diploid cells. In the presence of sufficient nutrients, these cells will grow as diploids. Starvation induces diploid cells to undergo meiosis and form four haploid spores.