In Class Questions Flashcards
State and describe 3 abiotic parameters that can be manipulated to control growth in food products. Give examples for each.
- Temperature - lower or higher kills or slows growth (example fridge/freezer)
- pH - neutral is favourable, increase acidity or base = kills (ex. Add vinegar/pickle it)
- Moisture - dry gives less nutrients (ex. Freeze dry/salt addition)
Define and describe “breakpoint chlorination”. Why is maintaining disinfectant residual important?
- breakpoint - consume everything that can be consumed
- residual ensures there is combat throughout transport
In the field of biotechnology, researchers can take advantage of “natural mutations”. State and describe an example of a natural mutation that can be useful.
- ice-plus is a mutation that bacteria supercools water at 0C and crystalizes above freezing
- Ice-minus (reverse mutation) lacks nucleating gene and protects plant from freezing/damage, plant can tolerate below freezing and bacteria is protected
State and briefly describe 3 reasons why some microorganisms may use fermentative metabolism. Name 2 environmental niches where you may expect to find fermentative bacteria.
- may be the only way to utilize/attack nutrients
–> in absence of electron acceptor organic compounds only catabolized by fermentation (less energy but supports growth) - too much competition - not enough resources for nutrition and survival any other way
- Nature of compound - easier to utilize than others, some cannot be attacked
- Niches = cow gut, wetland soil (anoxic)
Explain the fermentation pathway of clostridium propioncum (simplified)
- Starts with lactate –> pyruvate
- Creates ATP and acetate
- Feeds back on itself
- Picks up CoA to generate propionate and CoA transfer
- Feeds back on itself
Explain the fermentation pathway of clostridium propioncum (detailed)
- lactate oxidized to pyruvate
- pyruvate oxidized to acetyl-CoA and CO2
- acetyl CoA –> acetate and ATP (by acetyl-P)
- lactate acquires CoA from propionyl-CoA
- lactyl-CoA dehydrated to acrylyl-CoA
- acrylyl-CoA reduced to propionyl-CoA
Describe/define 2-component signalling in prokaryotes. State 2 examples where it is used
- signal transduction system that includes membrane-integrated sensor kinase protein and cytoplasmic response regulator protein. sends signal and communicates with flagellar motor.
- activation relies on getting it phosphorylated
–> ex. arc system senses changes in O2
–> ex. Che system senses concentration changes and controls flagellar motion
State and briefly describe 3 roles of Hsps under normal (non-stress) conditions
- Folds newly synthesized proteins at all temperatures
- exports proteins at all temp
- important role in growth at all temperatures
State and describe 3 abiotic features of the skin environment that might limit microbial occupancy
- low water activity, low moisture does not allow for growth
- exposure to UV which often kills bacteria
- skin lacks nutrition needed for bacteria to thrive
State and describe 2 areas of the human body where you may expect microbial occupancy. Which conditions favour this growth and why?
- Highest # found in colon where pH is neutral
- Colon also has fermentative bacteria that produce lactic acid and gas = larger space for bac growth - Oral cavity - saliva is source of certain nutrients and it is a moist environment
State and describe 5 factors/components associated with a bacterial cell that might support or contribute to its virulence
- enterotoxins that act on GI tract and cause massive secretion of fluid into intestinal fluid
- flagellum allow for motility, H-antigen allows for adherence
- O antigens inhibit demise in phagocytic cells
- Capsule is protective and antigen inhibits complement binding
- siderophores allow iron uptake and nutrients
Define and distinguish between “common source” epidemics and “person to person” epidemics. Provide an example for each.
- common source is a rapid rise to a peak of incidence because large numbers of individuals become ill in a short period of time (ex. foodborne/waterborne illness or COMMON COLD)
- person-to-person shows a slow, progressive rise to a gradual decline. can be initiated by one infected individual that infects 1+ people in the population (ex. chicken pox)
State an example of a vector-borne illness. What is the vector? Is it possible to eradicate the disease? Why/Why not?
- Malaria - vector is a mosquito. both humans and mosquitos are hosts to the parasite
- it is eradicated by case management, vaccines, pest control (of the vector), indoor residual spraying and insecticide treated nets
What is an ice-minus bacteria? give an example
- take advantage of a natural mutation
- protects crops from frostbite
- pseudomonas
Compare the human body to soil profiles
- Skin –> O horizon (UV exposure, dry, not a ton of nutrients)
- Colon –> A horizon (roots/nutrients, water and oxygen, pH neutral, temperature consistent)
