Microbial Growth – Flashcards

Unlock all answers in this set

Unlock answers
question
What are the 4 chemical rxns that aid in microbial growth?
answer
energy transformations, synthesis of monomers, polymerization of macromolecules, formation of cellular structures
question
What is binary fission
answer
starting with one cell that ends up into two daughter cells
question
what are determinants of population growth?
answer
growth rate, generation, generation time, exponential growth
question
Exponential growth
answer
phase of growth cycle where cells are moving at fastest growth
question
Growth cycle of populations: lag phase characteristics (3)
answer
seen with old inoculations, damaged cells, transfer from nutrient rich to nutrient poor media
question
Growth cycle of populations: exponential phase characteristics (3)
answer
cells in healthiest state, midexponential cells, rates of exponential growth can vary
question
When does exponential growth tail off?
answer
stationary phase
question
What growth phase are nutrients limited?
answer
stationary
question
What growth phase is there a buildup of waste products?
answer
the stationary phase
question
What growth phase do you have no net increase or decrease in cell number?
answer
stationary phase
question
What growth phase do you have cryptic growth (and what is cryptic growth)
answer
birth rate=death rate, stationary phase
question
What growth phase do you have sur genes?
answer
survival genes to conserve energy (stationary phase)
question
What is the death phase?
answer
more death than life --> net decrease in cells
question
What are the 4 phases growth curve?
answer
lag, exponential, stationary, death
question
Which growth phase is the longest?
answer
death
question
Which growth phase is the shortest?
answer
lag
question
What are the three characteristics of direct microscopic count?
answer
- dry or liquid methods
- counting chambers
- quick
question
What are the disadvantages of direct microscopic counting? 5
answer
1) cant distinguish dead from living
2) Small cells are difficult to see
3) precision is difficult to achieve
4) Phase contract for unstained specimens
5) not used with low density suspensions
question
What is viable count?
answer
plate count or colony count
question
What type of count assumes there is only one cell per colony?
answer
viable count
question
What measurement of growth technique spreads cells across plate?
answer
viable count
question
what measurement of growth uses the pour plate method (and what is it)
answer
viable count - it is having it on top of the agar plate
question
what measurement of growth uses dilutions?
answer
viable count
question
What are the sources of error in viable count? 3
answer
1) inoculum size, medium, and incubation conditions
2) Different growth rates
3) May underestimate numbers
question
What are the advantages of viable count?
answer
1) high sensitivity
2) select for different population
question
Measurement of growth: turbidometric methods: what does it measure?
answer
turbidity caused by a cell suspension (turbidity is proportion to cells present)
question
Measurement of growth: turbidometric methods. What does a photometer measure?
answer
Klett units *um what
question
Measurement of growth: turbidometric methods - what does a spectrophotometer measure?
answer
optical density
question
Measurement of growth: turbidometric methods - what does it measure
answer
unscattered light
question
Define turbidity
answer
proportional to cell numbers
question
What type of measurement growth must you prepare a standard curve?
answer
turbidometric methods
question
what happens in a turbidity measurement?
answer
scattering of light
question
how is the bug in a continuous culture?
answer
it stays in a steady state
question
Continuous culture: batch culture
answer
fixed volume of medium
question
Continuous culture
answer
flow system
question
continuous culture: steady state
answer
constant cell number and nutrient status
question
continuous culture: chemostat
answer
dilution rate, limiting nutrient
question
TF: in a chemostat, you will have cultures in 'stationary' all the time
answer
T
question
Effect of environment on growth: temp; what are the three cardinal temperatures?
answer
minimum, optimum, maximum
question
Temp classes: phychrophile
answer
4 degrees: polaromonas vacuolaa
question
Temp classes: mesophile
answer
39; escherichia coli
question
Temp classes: thermophile
answer
60; bacillus stearo-thermophilus
question
Temp classes: hyperthermophile ( lower level )
answer
88: thermococcus celer
question
Temp classes: hyperthermophile ( higher level )
answer
106: pyrolobus fumarii
question
What temp class is archea?
answer
hyperthermophile
question
TF bacteria is more acid tolerant than bacteria
answer
False, fungi is more acid tolerant
question
What kind of bacteria are acidophiles?
answer
acidophilic bacteria
question
In an acidophile, what do membranes depend on?
answer
low ph
question
picrophilus oshimae optimum for pH and temp
answer
.7 and 60 degrees
question
Where do you find alkaliphiles
answer
soda lakes and carbonate soils
question
what supplies energy for transport and motility in an alkaliphile?
answer
sodium gradient
question
what is the internal pH of an organism, no matter what
answer
neutral with relatively narrow range
question
What is plasmolysis
answer
cytoplasm shrinks away from cell wall
question
What do halophiles require?
answer
NaCl
question
Osmophiles like
answer
high sugar
question
xerophiles like
answer
very dry environments, they need to be able to rip nutrients from the H2O
question
What do aerobes tolerate?
answer
full O2 tensions
question
What is Microaerophiles relationship with O2
answer
(require O2 but does not need all O2)
question
what is microaerophiles tolerance for o2?
answer
less than 21%
question
what microorganism has a limited capacity for respiration?
answer
microaerophiles
question
What is an aerotolerant anaerobe?
answer
it is not killed by o2 but it wont grow in O2
question
What is an obligate anaerobe?
answer
Lives in the absence of air
question
What is a facultative anaerobe?
answer
makes ATP using aerobic respiration if air is present, if not it switches to fermentation
question
What is required for aerobes?
answer
aeration
question
What require exclusion of O2
answer
anaerobes
question
4 points under "anaerobes require exclusion of O2"
answer
- fill medium container completely
- reducing agent
- anerobe jar
- anaerobic glove boxes
question
Test tubes: what does an obligate anaerobe look like?
answer
concentration at the bottom
question
Test tubes: what does facultative look like?
answer
dense concentration at top and sporatically spread throughout
question
Test tubes: micro aerophile
answer
density right at top
question
Test tubes: aero tolerant
answer
spread evenly throughout
Get an explanation on any task
Get unstuck with the help of our AI assistant in seconds
New