Mid Term 1 Review Questions (Part 3.1) Flashcards
what is generation time?
the time it takes for a population to double
how do you calculate generation time?
final pop. = (initial pop.) * 2^n
where n = # of generations in x time
in what two environments do bacteria grow in nature?
- planktonic (free-floating)
- biolims
in what two environments do bacteria grow in nature?
- planktonic (free-floating)
- biolims
where can biofilms be formed? provide two good examples and two bad examples
good: bioremediation efforts use microbes to degrade harmful chemicals and are enhanced by biofilms. wastewater treatment facilities.
bad: tooth decay, gum disease, ear infections, gunk in sinks and toilet bowls.
why are biofilms hard to treat?
- microfilms within the biofilm often resist antibiotics and the body’s defense system.
- slime can’t be reduced chemically, but rather mechanically or physically.
- quorum sensing enable bacteria to work in their own benefit in mass
what is a mesophile?
why did Dr. Phadnis say biofilms are drug resistant? (5)
it’s a slow community in elders quorum. im out.
- decreased growth rates. most antibiotics target rapidly-dividing microorganisms.
- slime layer + community = hard for antimicrobial agents to penetrate
- over-expression of efflux pumps
- quorum sensing
- outer membrane proteins
what is a mesophile?
bacteria that grow most rapidly at medium temperatures, with the lower end of the temperature spectrum being soil, and the higher end being inside the human body
what is a psychrophile?
a bacteria that grows best in cold conditions
what is a thermophile?
a bacteria that grows best in warm to hot temperatures
what is an obligate aerobe?
organism that requires O2 for growth
what is an obligate anaerobe?
organism that cannot multiply and is often killed in the presence of O2
what are facultative anaerobes?
organism that grows best if O2 is available, but can also grow without it
what is a complex media?
don’t know how much of each element there is, ingredients are already synthesized
what is a defined media?
raw ingredients, you’ve got to synthesize everything, but you can control the conditions. you know exactly how much.
defined media, aka
slide into the DMs.
minimal medium
minimal medium, aka
defined medium
fancy name for complex medium?
nutrient broth
fancy name for defined medium?
glucose-salts broth
glucose-salts broth, aka
defined medium
nutrient broth, aka
complex medium
it’s techically a _____ defined medium?
chemically
when would i want to use a complex media? (2)
easy to make, used for routine purposes
when would i use a defined medium?
certain experiments when the type and quantity of nutrients must be precisely controlled
what is a differential media?
includes one or more ingredients that can be changed by certain bacteria in a recognizable way.
all bacteria are growing, but something differentiates them because you want to be able to tell them apart.
what is a selective media?
includes one or more ingredients that inhibit the growth of many unwanted organisms
basically, you only want A,C, and D from A,B,C,D, and E.
please name two examples of selective media
selecting where you auntie is gonna pee. (anti, pea)
- antibiotic-containing media
- PEA containing media (phenylethyl alcohol agar)
what is antibiotic-containing medium?
what type of media is it?
only antibiotic resistant strains can grow.
selective media.
what is PEA media?
what type of media is it?
phenylethyl alcohol agar.
only G+ can grow as G- outer membrane is destroyed by PEA.
selective media.
please name two examples of differential media
- blood agar
- they only taught us that one!
what type of media is blood agar, selective or differential?
how does it work?
differential.
causes certain cells to explode.
what is the main purpose of blood agar?
allows you to see which organisms grew and which ones didn’t
what is one disease that can be tested via blood agar?
strep
what three results appear on blood agar?
- alpha
- gama
- beta
what does beta mean in blood agar?
secreting an enzyme that busts open RBC
what does alpha mean in blood agar?
partial hemolysis
what does gama mean in blood agar?
no hemolysis
is selective media the same thing as selective conditions?
no
what test is both selective AND differential? (2)
- MacConkey agar
- Mannitol salt agar
what makes the difference in differential MacConkey agar?
changing colors
what makes up a selective MacConkey agar?
bile salts + dye
what makes up a differential MacConkey agar?
lactose + pH indicator
how does selective MacConkey agar work?
inhibits all BUT G- that typically reside in the intestine
how does differential MacConkey agar work?
why?
lactose fermenters are red/pink because low pH allows them to take in dye
what also must happen for cultivating bacteria in the lab to work?
must also provide the correct atmospheric conditions
how does Mannitol salt agar work?
what is it selective for and against?
salt inhibits most bacteria.
selective for: G+
selective against: most G-
mannitol salt agar, aka
MSA
MSA, aka
mannitol salt agar
what is the readout of MacConkey agar?
pink = lactose fermenter
not pink = not lactose fermenter
what is the readout of mannitol salt agar?
yellow = ferment mannitol
pink = can’t ferment mannitol
