Yeasts and molds (Saccharomyces Cerevisiae) Flashcards
What is a fungus?
Any group of spore-producing organisms feeding on organic matter, including molds, yeast, mushrooms and toadstools,
What is a mold?
A fungus that grows in the form of multicellular filaments called hyphae
What is a yeast?
A microscopic fungus consisting of single oval cells that reproduce by budding, and are capable of converting surgar into alcohol and carbon dioxide
S.Cerevisiae is a species of ____________ yeast
budding
In nature Sc is generally found on the surfaces of __________
ripe fruits
Sc has _______ chromosomes
16
Sc is known for its ability to utilize ________ in formation of ethanol and other by-products
carbohydrates
In the Gay-Lussac Equation 180g sugar is converted to ____g Ethanol and ___g CO2
92, 88
Sc can exist in both a ________ or a ________ (think of its cell cycle)
haploid, diploid
If _____________ are present both haploids and diploids can undergo repeated rounds of vegetative growth and mitosis
adequate nutrients
When nutrients become depleted, both haploids and diploids arrest as ______________
stationary phase cells
Stationary phase cells are ____________ and __________ distinct from proliferating yeast cells
morphologically and biochemically
Stationary phase cells round and bright and contain much higher levels of ____________________ than proliferating cells
storage carbohydrates (trehalose and glycogen)
TRUE OR FALSE: Stationary phase cells also have an increased resistance to a number of stresses and environmental conditions when compared to growing cells
TRUE
Haploid cells can exist in one of two mating types ______
a or 𝝰
Mating type a produce a pheromone _______
Mating type 𝝰 produce a pheromone ______
a factor
𝝰 factor
Each cell type has the surface receptor for the __________ mating type. If the surface receptor is stimulated the cells arrest in the _________ of their cell cycle
opposite
G1 phase
When the haploid cells arrest in the G1 phase of growth they no longer proliferate but start ________________. The resultant shape is called________
growing towards each other
Shmoo
Eventually there is cell contact, _________, and a diploid is formed
fusion
Diploid cells that are starved of nitrogen will undergo _________ and ________
meiosis and spore formation
4 haploid spores are formed and contained in an _____
ascus, an ascus has even greater resistance to environmental factors than stationary phase cells
If the spores are returned to a rich environment they will _________ and _____________ as haploid cells
germinate and commence growth
Sc vegetative proliferation occurs via __________
budding
The cell cycle comprises several ______________where the progression of the cell cycle is prevented if certain necessary processes have not taken place
checkpoint controls
Mitosis will not happen if ______________has not been completed
DNA replication
There are several morphogenic aspects of the yeast cell cycle:
(name the 4)
1) Bud-site selection: in rich media haploids bud in axial pattern where diploids show polar budding
2) Polarity
3) Pattern
4) Rate of growth
Since yeast has a cell wall, growth can only occur where new __________ and cell wall _____________ are delivered.
cell wall material, remodeling enzymes
Growing Sc cells ferment _______ via glycolysis to form ethanol. In Stationary phase cells use _________ formed in earlier stages via the TCA and glyoxylate cycles
glucose, the ethanol
Most compounds required for Sc metabolism are not able to pass through ___________________, and therefore must be transported via specific transport proteins
the phospholipid membrane
________ and _________ are exceptions to this rule and can diffuse easily across the cell membrane
ethanol and glycerol
Some carbohydrates, specifically disaccharides, undergo ____________ by secreted _________________, and the resultant hexoses are taken up by the cell
extracellular hydrolysis
invertase or galactosidase
____________ is an important carbon source for yeast during brewing and bread-making
Maltose
Maltose is actively transported across the cellular membrane, and then hydrolyzed via into two glucose molecules
𝝰-glucosidase (AKA maltase)
The cell wall of Sc offers _____________ against physical damage and plays a major role in morphogenesis
mechanical strength
___________ compose approximately 50% of the cell wall, while _____________ make up 40% and __________ accounts for the remaining 10%
Glucans
mannoproteins
Chitin
_________ (also known as koji) is used mainly in East Asian cuisine to ferment soy beans, make soy sauce, miso, and break down rice starches into sugars for making sake
Aspergillus oryzae
It secretes a selection of ____________ that extracellularly degrade starch to glucose
amylases
Name 2 species of amylases
1) endoamylases
2) exoamylases
Aspergillus oryzae:
1) Conidium 2) Swollen Conidium 3) _____________ 4) ___________
3) germling tube
4) differentiated hypha
A.oryzae is a __________ fungi
filamentous
What is a conidium
It is a spore that is produced asexually by A. oryzae fungi at the tip of a specialized hypha that is capable of growing into a new multicellular organism
If the conditions are right the conidium will _________ and eventually grow into a ___________ that will eventually form the hyphae
swell
germ tube
The ________ are the individual sections that are partitioned by ________ and constitute multicellular filamentous fungi
hyphae
septa
how does the grow of fungi occurs
The growth of the fungi occurs via extension of a highly metabolically active hyphal tip
There is a ______ located in the middle of each septum that allows for communication between cells
pore
What happens if one cell is killed or damaged ? (A.oryzae)
Woronin bodies are grouped near the septum and will plug the pore if it detects cell damage
A. oryzae secretes a selection of _________ that extracellularly degrade starch
amylases
What is Spitzenkorper in Aspergillus oryzae?
A specific organelle of A.oryzae that is present in the hyphal tip region and is involved in the accumulation and secretion of vesicles that contain secretory enzymes.
The secretion vesical is then _________ immediately after fusion with the cell membrane, and is then immediately recycled for incorporation into new secretion vesicles
endocytosed
Why is the recycling of secretion vesical important for A.oryzae?
It is critical for sustaining high levels of amylases
The ______________ is a special cell that is designed to produce conidium to spread the mold
conidiophore
Nutrients are passed from the________ and up to the budding ____________
hyphae, budding
When conditions are right the conidium prepares to germinate. The first step is _______
to swell
Name 3 other molds:
- Geotrichum candidum
- Penicillium candidum
- Penicillium roqueforti
Geotrichum candidum (name a characteristic)
A rapid growing mold that prevents unwanted mold growth in moist cheeses
Penicillium candidum (name a characteristic)
Produces the fuzzy white mold on the surface of bloomy rind cheeses including Brie, Camembert, Coulommiers, and French goat cheeses
Penicilium roqueforti (name a characteristic)
Creates the colored veins and surfaces and is a major contributor to the flavor in blue cheeses including Gorgonzola, Roquefort
Yeasts and molds provide nutrients to _________
LAB
_________ and __________ are anerobic
Molds and AAB
___________ and ________ are anaerobic
LAB and yeasts
Give a few characteristics of sake :
- Is a traditional Japanese alcoholic drink
- Also known as Japanese Rice Wine
- Sake generally contains 18-20% ABV (wine is 9-16%, beer is 3-9%)
- On special events sake is gently warmed and served in a porcelain bottle or sipped from a porcelain cup
- The optimal serving temperature varies by type
what do you need to make sake (4)?
water, rice, koji and yeast
What is Fukuyama Pot Vinegar?
a traditional Japanese rice vinegar where rice and koji are added without additional organisms to a loosely capped large pot and laid in an open-air field
What are the reaction happening in Fukuyama Pot Vinegar?
- Saccharification
- Alcohol fermentation
- Acetic acid fermentation
- Lactic acid fermentation
How do you make milk kefir?
beverage milk is inoculated with kefir grains that harbor LAB, AAB, and yeast (and sometimes molds)
what is kefiran?
an extracellular polysaccharide that is produced by the LAB found in kefir grains
