yeast and mold Flashcards
Saccharomyces cerevisiae
budding yeast species
- yeasts are known as “sugar molds”
- single cell
- cannot be airborne (needs a vector)
- 16 chromosomes
Gay-Lussac Equation
reaction describing the metabolic process of yeast
glucose is converted to 2ethanol and 2carbon dioxide
Is Sc haploid or diploid?
can be either
If there is adequate nutrients both haploid and diploid cells can grow in the vegetative state or undergo mitosis
*stationary phase cells
- morphologically and biochemically different distinct from proliferating yeast cells.
- Contain much higher concentrations of storage carbohydrates (glycogen, trehalose)
- increased resistance to stresses and environmental conditions
what are the 2 mating types of haploid yeast cells?
alpha and a
alpha produce the pheromone alpha factor
a produce the pheromone a factor
-each binds to a receptor located on the opposite type of cell
When do diploid yeast cells undergo meiosis
when they are starved of N
How are diploid yeast cells formed?
- receptor is stimulated
- cells arrest in the G1 stage
- cells begin to grow towards one another forming a shmoo
- when the cells contact there is fusion and a diploid cell is formed
ascus
4 haploid cells are contained in an ascus, which has even greater resistance to stressors and environmental factors than stationary cells
how do yeast cells bud?
haploid: on the same side
diploid: opposite sides
what metabolisms of yeast occur in the stationary phase?
cells use the ethanol formed in earlier stages via TCA and glyoxylate cycles
What metabolisms of yeast occur in the proliferating state?
fermentation of sugars to ethanol and CO2
are compounds needed for Sc metabolisms easily transported across the membrane?
NO, they need transporters
Exceptions: ethanol and glycerol
sometimes extracellular disaccharides are hydrolyzed outside the cell, so they can be transported inside the cell
What is the metabolism of maltose?
- maltose breaks down into 2 glucose by maltase (alpha glucosidase)
- maltose is transported across the membrane
invertase
hydrolyzes sucrose into fructose and glucose
what material gives the cell wall its strength?
chitin
Aspergillus Oryzae
used to ferment soy beans, make soy sauce, and break down rice starches
How does Aspergillus Oryzae break down starch
starch is broken down into glucose via amylase
*condidium
spore produced asexually capable of growing into a multicellular organism
*germ tube
conidium swells into a germ tube, which eventually forms hyphae
*pore
septums separate the cells of the hyphae. Pores are located in the middle of each septum, which allow the cells to communicate with each other
*Woronin bodies
group near the septum and plug the pore if the cell detects damage
*hyphae
constitute the multicellular filamentous fungi
*setum
separates the cells of the hyphae
Spitzenkorper
located at the hypae tip. involved in the accumulation and secretion of vesicles that contain secretory enzymes
secretory vesicles are then recycled/endocytosed.
conidiopore
produce conidium to spread the mold. Nutrients are passed through the fungi and stored in the budding conidium
