Saccharomyces cerevisiae
What is Saccharomyces cerevisiae used in industry for?
Beer and bread making
What is Saccharomyces cerevisiae's metabolism?
Chemoorganotroph, facultative anaerobe: glycolysis, oxi/phos, fermentation
Describe the haploid life cycle of Saccharomyces cerevisiae
Divides by simple budding
Organization of Saccharomyces cerevisiae
Eukaryote, cell wall, no flagella (non-motile), Fungus: cell wall, no chlorophyll
How do MAT cells know abou their surroundings?
Excrete and sense pheromones from opposite Mating type cell
What are the two kinds of mating types of Saccharomyces cerevisiae?
a and alpha
What are the roles of MAT proteins?
alpha 1: repressor of a-specific genes a1 and alpha-1: no role in haploid, diploid they form a complex that represses alpha specfic enes and activates diploid specific genes
What is shmooing?
extension of part of the cell wall to reach out and contact other cells as they are non-motile
How does Saccharomyces cerevisiae deal with nutrient deprivation and dessication?
forms sporulates, goes through sexual reproduction
What is the process when a pheromone is bound?
pheromone receptors are linked to g-proteins which start a signaling cascade that results in the expression of genes that lead to shmooing, cell wall fusion and nucelar fusion.
When does mating type switch occer?
The new bud from a mother cell has a different mating type. Only cells that have undergone a division can switch mating types
What are the requirements for two cells to mate?
1. Know mating partner is near 2. Contact partner 3. Fuse cell walls 4. Fuse nuclei
What are the purposes of Pheremones?
1. Know that a compatible mating partner is near 2. Conact the partner 3. Initiate shmooing 4. Fuse cell wall 5. Fuse nuclei
What is the transcription factor that is at the end of the signal cascade initiated by a pheromone?
STE-12, initiates gene trasncription for cell wall fusion nuclear fusion shmooing
What is unique about Saccharomyces cerevisiae's response to poor nutrition and dehydration?
Has to be in diploid form, allows for sporulates to form. Resistant form of organisms, allows for survival in adverse conditions.
Growth and Development of Saccharomyces cerevisiae
Increases diameter, develops long filaments and becomes invasive in response to nutrient deprivation
What is the purpose of switching mating types?
It ensures equal numbers of each mating type
What is unique about Saccharomyces cerevisiae's response to poor nutrition?
It has to be in haploid form, and allows for invasion of fruit tissues
What do mating type locuses do?
MAT a: has genes for proteins a1 MAT alpha: has genes for proteins alpha1 and alpha 2
What are the two outcomes of sexual resproduction?
Mitosis: simple budding Meiosis: forms sporulates, 2 a forms, 2 alpha forms both haploid.
