9.2.2022. IS questions Flashcards
When we talk about microbial growth, to what are we referring?
binary fission, growth of a population of bacteria
If you start with a population of 100 cells of a species that has a generation time of 20 minutes, how many cells will you have two hours later? How many generations have occured?
xf = xi * 2^n
What is a biofilm?? Give an example of where you can find a biofilm in your environment
polymer-encased community of microorganisms. slippery rocks on a stream bed, dental plaque.
What is a pure culture?
a population descended from a single cell
What is a solid versus a broth medium?
solid medium vs. liquid medium. nutrients dissolved in water. growth curve happens in broth.
Name two methods to sterilize media
- heat (flame)
- disinfection
What is generation time?
The time it takes for a population to double in number
What are the two types of bacterial growth in nature?
- Free floating (aka planktonic)
- Biofilms (polymer-encased communities of microorganisms)
What is a psychrophile?
cold. artic and antartic
What is a mesophile?
middle. ex. humans (warmer end) or soil (colder end)
What is a thermophile?
heat. ex. hot springs and compost heaps
what is an obligate aerobe?
facultative anaerobe?
obligate anaerobe?
- must have air
- grow better if O2 is present, but grow without it
- can’t multiply if O2 is present
what is the role of superoxide dismutase?
enzyme that degrades superoxide to produce hydrogen peroxide
what is the role of catalase?
enzyme that breaks down hydrogen peroxide (H2O2) to produce water (H2O) and oxygen gas (O2).
what is a halophile?
prefers/requires high salt (NaCl) to grow
