5) Saccharomyces Cerivisae Flashcards
what type of yeast is Sc?
budding
Can Sc be airborne?
no
it needs a vector to move
how many chromosomes does Sc have?
16
what is the Gay Lussac Equation?
180g sugar –> 92g ethanol + 88g CO2 (theoretical yield)
what are two forms that Sc can exist as?
haploid or diploid
what occurs to haploids and diploids when there are adequate nutrients present?
haploids and diploids both undergo repeated rounds of vegetative growth and mitosis
what happens to Sc when nutrients are depleted?
haploids and diploids arrest as SPC (stationary phase cells)
what are SPC? characteristics?
how are SPC different than proliferating/growing yeast cells
- SPC = stationary phase cells
- round and bright
- contains more storage CHO (trehalose and glycogen) than growing cells
- higher resistance to stresses than growing cells
what are the 2 mating types of haploid cells?
differentiate them.
what surface receptors do they have?
a: produces a pheromone “a factor”
alpha: produces “alpha factor”
each cell type has the surface receptor for the opposite mating type
what happens when the surface receptor on one of the mating haploid types is stimulated?
- cels stop in the G2 phase of the cell cycle
- cells stop proliferating and grow towards each oterh
- creates a “shmoo”
- once there is cell contact, they fuse together and form a diploid
diploid cells with no N will undergo ____ and ____.
what does this create?
meiosis and spore formulation, which results in 4 haploid spores contained in an ascus
what is an ascus? how does it compare to SPC?
- contains 4 haploid spores after sporulation
- has higher resistance to stresses than SPC
Sc vegetative proliferation occurs via _____
budding
what does the cell cycle have to control processes that occur?
checkpoint controls, where the cell cycle doesn’t continue if some processes haven’t happened (eg. mitosis won’t happen if DNA replication has not been completed)
what are 4 morphogenic aspects of the yeast cell cycle
- bud site selection: in rich media, haploids bud in an axial pattern, while diploids show polar budding
- polarity
- pattern
- rate of growth
how does growth occur in yeast?
building materials are packed into vesicles, docked at the plasma membrane, then incorporated into the growing cells
differentiate the products and substrates of growing and stationary phase
growing phase: Sc cells ferment glucose via glycolysis to form ethanol
stationary: Sc cells use ethanol already formed via TCA and glyoxylate cycles
why do Sc have specific transport proteins?
b/c most compounds needed for Sc metabolism can’t pass through phospholipid membranes, thus they must be transported through
describe the breakdown of maltose by Sc
- actively transported across the cell membrane
- hydrolyzed by alpha-glucosidase (aka maltase) to produce 2 glucose molecules
- glucose is broken down in glycolytic pathway
describe the breakdown of sucrose by Sc
sucrose is broken down to fructose + glucose (via invertase)
describe the cell walls of Sc
- cell walls have mechanical strength against physical damage
- has a homogenous inner layer (plasma membrane) and a fibrillary outer layer (implanted in inner layer and emanating from cell surface)
- composition: glucans, mannoproteins, chitin (most responsible for mechanical strength of cell wall)
what is around 50% composition of cell wall?
glucans
what are 2 types of amylases
- endoamylase: alpha amylase (breaks down alpha 1,4 links)
2. exoamylase: beta amylase (breaks down alpha 1,4 links) and gluco-amylase (Breaks down alpha 1,4 and alpha 1,3)
what is another name for oryzae
koji
