Exam 3 Quiz 2 Flashcards
Cocci Bianary fission
-dont have MreB
-caulobacter
-FtsZ ring
-Min C D E dont play a role
-active point of research
when do antibiotics have an effect
the cell needs to be actively growing
vasotracin
topical, inhibiting bactoprenol
biofilm
-mushroom organization of bacteria
-antibiotics are not that effective on these
caulobacter
MreB and CreS
exponential growth
constant rate of growth, cell number doubles in regular time interval
mathematics of growth
predict the number of bacteria cells that will arise during a growth period
growth
fixed relationship between the initial number of bacteria and after a specific time period
equation for growth
Nt=N02n
Nt
population at time t
N0
initial population number
n
number of generations in time t
mean growth rate
log Nt - log N0 / (0.031)(t)
generation doubling time
1/k
k
n / t
batch culture
closed system, done in a test tube or flask
batch culture growth curve
-lag phase
-exponential growth phase
-stationary phase
-death phasel
lag phase
-shortest phase
-variable in time (30 mins - 5+ hrs)
- time depends on the size of the initial culture
exponential growth phase
-nutrients there
-bacteria living at best/grow at their max
-cont last forever because the system is closed
stationary phase
-equaling out bacteria growth
-see some decline bc of nutrient loss
-build-up of toxic wastes
death phase
bacterial decline at exponential rate
in the stationary phase we see
nutrient decline and persister cells show up, go into starvation mode and upregulate different proteins
persister cells
live because of cryptic growth, grows off of their neighbors
upregulation of proteins
-increase crosslinking in peptidoglycan
-increase chaperone protein to protect DNA
-bind enzymes to prevent denaturing
viable but nonculturable state (VBNC)
-can come back with a lot of care
-makes use of antibiotics important and difficult
big disadvantage to viable counts
requires culturing and can only culture 1% of bacteria
viable counts
way to get all the numbers used in the equations
good colony count
30-300, if two viable to count , use the lower dilution (higher count)
units for colony count
colony forming units per mL
how to determine cfu/mL
plate count x DF x 1/amount plated
DF
dilution factor
hemocytometer
-easier to count
-have individual bacteria counts
-can count dead and alive cells
-have higher count bc individual cells but mainly bc It COUNTS EVERYTHING
-dilution still required
-faster
spectrophotometer
-turbidity
-need to make a standard curve
-only use preidentified
-measures absorbance
flow cytometer
hydrodynamic
-needs a light source
-can get forward and side scattered
-gives more info
foreward
gives cell size
side scattered
gives cell granularity/ density inside cells
continuous culture system
-chemostat
-specific growth rate and cell density can be independently controlled
what controls specific growth rate
dilution rate
what controls density
concentration of a limiting nutrient
dilution rate
rate at which new media is added and old media is taken out
Temperature effects of microbial growth
bacteria cant thermoregulate, they are completely susceptible to their environement
temperature range is defined by
three cardinal temperatures
three cardinal temperatures
-minimum temperature
-optimum temperature
-maximum temperature
what helps manage temperature
-enzymes (maximum end)
-cell membrane (minimum end)
optimum temperature
usually lies closer to maximum because thing happen faster in warmer environments (active sites)
eukaryotic cutoff
65 C
bacteria cutoff
95 C
archaea temps
above 95C
order of microbe classes by temperature
-psychrophile
-mesophile
-thermophile
-hyperthermophile
psychrophile
-15C or less
-live in constantly cold environments (usually 1-5C)
-oceans and frozen land
psychrotolerants
-things that extend their ranges to grow in colder environments
-ex. continue to grow when put in the fridge
-listeria monocytogenes
enzymes/proteins of psychrophiles
-more alpha helix
-more polar, less hydrophobic interactions
-cold shock/chaperone proteins
membrane of psychrophiles
-unsaturated fatty acid with shorter chain
-more cryoprotectants
-extra coating called exopolysaccharide layer
cryoprotectants
-offset freezing point inside a cell
-have glycerol and sugars
exopolysaccharide layer
-extra layer of insulation
-sticky, commonly seen in biofilms
