Principles of Micro 4 Flashcards
what are the two types of cell inclusions in bacteria
glycogen and polyphosphate
where are the cell inclusion found and what are their functions
glycogen: found in many species, carbon and energy storage
polyphosphate: found in many species, phosphate storage
are endospores mainly gram pos or gram neg
main gram pos
just recently found one gram neg one
what is the importance of endospores
they shut down protein, enzymatic, and macromolecular synthesis and wait
they are important for heat, chemical, and radiation resistance for bacteria
what are the three locations for bacterial cell in endospores
terminal - all the way to one end
central - in the middle
subterminal - almost all the way to one end
name the endospore formers
c. difficile
c. botulinum
c. tetani
b. cereus
what is so important about c. difficile
significant for infection control
describe sporulation and germination
in harsh environment, bacteria cells undergoes sporulation where it replicates and produces a spore while the original cell dies (take 6-8hrs)
then in favorable environment, the spore germinates back to bacteria taking 1 - 2 hrs
what are components that influence growth of microorganism
temperature, pH, water, carbon and energy sources, trace elements
how does temperature influence growth rate of microorganism
there is an optimum range for microorganism growth
also there is a min and max temp where microorganism do not grow
name the temperature categories in which microorganisms fall under; what the optimum temp is in degree celsius; and if medically significant
psychrotrophs and psychrophiles - 15 oC - No
Mesophiles - 20-40 oC - Yes
thermophiles - 50-60 oC - No
what is the difference between pyschrotrophs and psychrophiles
psychrophiles are cold loving and actually handle temperatures as low as 2 - 3 oC while psychrotrophs can tolerate the cold weather so their optimum is only 15 oC
random pop quiz: what is a firmly attached polysaccharide layer that is located external to the cell wall/outer membrane which enables bacterial evasion one of the host non specific defenses
capsule
list the pH categories in which microorganisms fall under and what pH they can handle
extreme acidophiles: 0-2 acidophiles: 3 - 5 neutrophiles: 6 -8 alkalophiles: 9 - 11 extreme alkalophiles: 12-14
list the ranges of water availability in which microorganisms can thrive/not thrive
.93 - .98: no growth of gram positive bacteria
.97 - no growth of gram neg bacteria
less than .93 - most spoilage due to yeast and fungi
less than .9 - most bacterial unable to grow
less than .6 - no microbial growth
what do all organisms need
carbon and energy source
what are way in which organisms can get energy
chemotrophs - chemical energy
phototrophs - light energy
examples of phototrophs
plants, algae, photosynthetic bacteria
what are two types of chemotrophs
chemolithotrophs - use inorganic sources of carbon
chemoorganotrophs (heterotrophs) - use organic sources of carbon (most bacteria)
examples of chemoorganotrophs aka heterotrophs
bacteria, fungi, protozoa, humans
what sources can you get the following elements from: carbon, oxygen, nitrogen, hydrogen, phosphorus, sulfur
carbon (50%) - cellular material
oxygen (20%) - cell material and cell water, 02 is an electron acceptor in aerobic respiration
nitrogen - AA, nucleic acid nucleotides, coenzymes
hydrogen - organic compounds and water
phosphorus - nucleic acids, nucleotides, phospholipids, LPS, techoic acid
sulfur - glutathione, cysteine, methionine, several coenzymes
what are trace elements usually needed by microorganisms
usually metal ions - zinc cobalt for ex
enzymes needed in energy generation
organic growth factors like vitamins and minerals
do all microorganisms need organic growth factors
no some of them synthesize their own
what pathogen requires nicotinamide
bordetella pertussis
what pathogen requires X and V factor
haemophilus sp.
in an unshaken culture, describe where each type of microorganisms in relation to their oxygen requirements
top only - obligate aerobes
evenly distributed - facultative anaerobe and aerotolerant anaerobe
slightly below surface - microaerophile
what is difference between facultative anaerobe and aerotolerant anaerobe
facultative - use O2 if present but if not will use something else
aerotolerant - indifferent to O2, even in their presence they won’t use them, need non O2 requirements
what are obligate anaerobes and why are they not present in the unshaken cultures
they must be in an area without any oxygen or they will not grow
not in unshaken culture because they only grow in specially prepared media/conditions
which group of microorganisms use catalase and superoxide dismutase
obligate aerobes and most facultative anaerobes
which group of microorganisms use only superoxide dismutase
most aerotolerant anaerobes
which group of microorganisms use neither catalase or superoxide dismutase
obligate anaerobes
what is the catalase test and what does it show?
place a few drops of peroxide onto a glass
then mix in a loopful of single colony
then what for immediate fizzing
if bubbles = positive catalase test
it shows that O2 is present in colony and that colony must be obligate aerobes or facultative anaerobes
binary fission continues until what happens
the nutrients have been exhausted and conditions become unfavorable
name the generation for the amount of cells listed
2 cells
8 cells
16 cells
64 cells
2 = 1st generation 8 = 3rd generation 16 = 4th generation 64 = 6th generation
describe the growth curve
in a closed system, first there is the lag phase where the cells are adapting to their environment
then there’s the log phase, where the cells increase exponentially
then there’s the stationary phase where the nutrients are starting to run out and the number of new cells = the new of cell dying
then there’s death where there is decreasing amounts of viable cells
what is finite in relation to the growth curve
nutrients and space; no waste products removed
what is serial dilutions
case where the original culture is diluted serially until it is possible to count the amount of culture on the plate
what is the equation to figure out the number of bacteria in the original sample
dilution sampled (positive) * volume of liquid in which the sample was taken out of * # visible colonies after dilution
# of visible colonies after incubation = 40
Dilution sampled = 10^-3
Volume of sample plates = 0.1 mL
what is the number of bacteria in the original sample
40 * 10^3 * 10 = 400,000 CFU/mL
Calculate the CFU per mL of the original bacterial or fungal culture using the data provided:
42 colonies from 0.1ml plated of 10^-3 dilution
42 * 10 * 10 ^3 = 420,000 CFU/mL
Calculate the CFU per mL of the original bacterial or fungal culture using the data provided:
37 colonies from 0.25ml plated of 10^-6 dilution
37 * 10^6 * 4 = 1.48 * 10^8
what type of graphs are preferred for more accurate cell numbers during growth
logarithmic graphs
what equations are used to calculate generation time
n = Log N‐ Log No /0.301 g = t/n
where N = total population No = initial population t = time g = generation time n = number of generations
what is the importance of generation time
it tells the incubation period and how long until one starts to see symptoms
Calculate the generation time (g) using the following data
No = 1.2 x 10^3; N = 3.8 x 10^9; t = 420minutes
n = (9.58 - 3.08)/ .301 = 22
g = 420/22 = 19
to culture media, what three things need to be know
physical state, composition, function/purpose
what are two types of composition
synthetic/defined - where all the components are known
complex/non synthetic - where the components are vague
when will you use TSB and what are the components
general purpose
macronutrients, micronutrients, carbon source
when will you use blood agar and BCYE agar and what are the components
enrichment
general purpose plus blood, serum, antibiotics
when will you use MacConkeys and what are the components
selection and differentiation
salts, dyes (brilliant green), antibiotics
SAD DSM
when will you use Stuart’s media and what are the components
transportation
buffers, no nutrients/carbon source
when will you use Mueller Hinton Agar and what are the components
assay eg. antibiotic sensitivity
carefully defined formula
