week 3 Flashcards
binary fission
- asexual reproduction
- bacteria and archaea
- exponential increase in population
- replicate and segregate BEFORE dividing
what are the phases of the bacterial growth curve?
lag, exponential, stationary, death, and long-term stationary
lag phase
- no bacterial growth
- preps for division so like the synthesis of new components and DNA replication
exponential phase
grows as quickly as possible in the conditions available
stationary phase
- growth stops due to nutrients and O2 being less available
death phase
exponential decrease in living cells
long-term stationary phase
evolution occurs with the remaining cells
most microbes live in what kind of an environment?
hypotonic
hypotonic def
there is less solute outside the cell than inside and the cell wall is what keeps it that way
take a look at the equations
4 (+2) cardinal factors that affect bacterial growth
temperature, O2 concentration, pH, water activity
pressure and radiation
5 groups of microbes in regards to temp.
psychrophiles: 0-20C
psychrotolerants: 0-35
mesophiles: 20-45
thermophiles: 45-85
hyperthermophiles: 85-100
5 groups of microbes in regards to O2 conc.
- obligate aerobic: requires O2
- microaerophile: requires low O2
- facultative anaerobe: does not require but grows better with O2
- aerotolerant anaerobe: grows w/ or w/o O2
- strict anaerobe: killed in O2
2 groups in regards to pH
acidophiles: 0-5.5
alkaliphiles: 8-11.5
osmophiles
microbes that have adapted to a hypertonic environment and need high salt conc.
2 kinds of osmophiles
halophiles: 0.2M
extreme halophiles: 3-6.2M
what are biofilms?
it is an environment where a community of microorgs (which may be different species) come together, communicate, and thrive in favorable conditions
biofilms have a key property that is “there is power in blank”
- numbers
- “stronger together”
examples of biofilms
medical devices, sewege system, shipping industry and plaque on teeth
quorum sensing
- cell to cell communication via autoinducers. They diffuse into the environment and send signals to other cells.
- There has to be enough microbes participating in the biofilm for it to work
physical techniques regarding microbial growth/elimination
filtration, sterilization, radiation
filtration tech.
removes microorgs in heat sensitive materials
3 ways of sterilization tech.
- autoclave: steam
- dry heat: less effective than autoclaving, higher temp, more exposure time, does not melt glass, just plastics
- pasteurization: less temp, kills and slows spoilage but doesn’t sterilize,
2 ways of radiation tech.
-UV: causes thymine dimers which prevents replication
ionization: gamma radiation dislodges the electrons creating free radicals
chemical techniques regarding microbial growth/elimination
- phenolics- disinfectants (lysol)
-alcohols- denatures proteins and membrane lipids - halogens- oxidizing agents (I2 or Cl2)
- heavy metals- inactivate proteins (mercury, silver, zinc)
- antibiotics- natural pdts that kill microbes or inhibit growth (penicillin, sulfa drugs (prontosil red), streptomycin)
ways to count viable cells
- standard plate counts
- counting chamber (grids)
- membrane filter tech. (filtered, stained)
- flow cytometry (a tube so narrow that only one cell can pass at a time)
penicillin info
- fleming
- has an effect on gram (+)
- treats strep.
sulfa drugs (prontosil red) info
- Donagsk
- protect w/o toxicity
- treats staph
streptomycin
- Waksman
- has an effect on gram (-)
- treats TB
arsenic info
- Erhilic
- 1st chemo: poisonous but kills microbes
- treats syphilis
-cide
kills
- MIC (inhibitory)
-static
inhibits growth
- MLC (lethal)
3 ways to measure the effectiveness of the antimicrobial activity of drugs
- dilution: add in the MLC and MIC and see how well they work
- disk- kirby bauer method: measure the diameter of the antimicrobial-ness
- e-test: the strip has antibiotics on it and whenever the bacteria starts to form just correlate the number of the strip with it
what inhibits the synthesis of the cell wall?
- penicilin
- cephalosporins
- vancomycin
what inhibits ribosomal function/synthesis?
- macrolides (50S)
- aminoglycosides (30S)
- chloramphenicol (23S)
- tetracyclines (16S)
what inhibits metabolic pathways?
- sulfa drugs
- trimethoprim (similar to sulfa)
what inhibits nucleic acid synthesis?
- fluoroquinolones
- rifamycins
why are there limitations for drugs that are antiprotozoan and antifungal?
- They are eukaryotic and too similar to our cells
- antip: plasmodium treats malaria and quinine
2 types of drug resistance
- intrinsic- resistant due to lacking the thing that the drug targets
—-ex: mycoplasma resistant to B-lactam antibiotics bc it targets the cell wall and bacterias lack a cell wall - acquired- a change happened in the genome that caused it to be resistant
