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25 Cards in this Set

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macronutrients
C,H,O,N,P,S,K,Mg,Ca,and Fe
Fe3+ transported into cells as chelate (hydroxomates)
oxic conditions: exist in insoluable minerals (ferric).cells produce siderophores that bind to Fe3+ forming iron chelates. Fe is transported as chelate into the cell.Hydroxomates are the most common siderophore.
anoxic:Fe2+
Fe3+ transported into cells as chelate (enterobactins)
coliform bacteria produce very powerful phenolic siderophores,enterobactins. they are important for pathogenicity bc Fe is scarce in animal tissues. (rip Fe from heme, O2 bind Fe and chelates)
Fe3+ with marine environments
virtually undetectable
aquachelins by marine organisms have peptide head and hydrophobic tail. Aggregate in blobs and transport bound Fe into cell
not all microorganisms require Fe
lactobacillus plantarum and borrelia burgodorferi
Mn2+ substitutes Fe
micronutrients(trace elements)
typically metals, tiny amts
catalysis, enzyme components
trace elements
boron
chromium
cobalt
copper
present in an autoinducer
mammals, glucose metabolism
vit B12
respiration,photosynthesis
trace elements continued...
iron
manganese
nickel
selenium
cytochromes,catalases
enzyme activator
hydrogenases
formate dehydrogenase
last of trace elements
tungsten
vanadium
zinc
formate dehydrogenase
nitrogenase
carbonic anhydrase, alcohol
growth factors
organic compounds, small amts
most are vit's, but can be purine,pyrimidine, and aa
culture media
most microos cant be cultured
defined:mix exact amts of pure chemicals
undefined:(complete)unknown chemical composition(broths)
[micro cultured in simple defined, complex defined or complex undefined]
complex undefined medium
(ecoli, l.mesenteroides)
glu,yeast,peptone,distilled with pH of 7
start with complex medium and add serum or whole blood to mimic the host
presentations of media
liquid vs solid
liquid:suspended cultures
medium:agar slant
warm,sterile,med:agar into petri dish and solidify at RT
aseptic technique for cell transfer`
heat loop
uncap tube
run tip of tube thru flame
sample removed on sterileloop
tube reflamed,sample transferred to a sterile med
recap tube, reheat loop
intitial collection or isolation of microorgansims
initial sample:soil,sewage,blood,urine,mouth or skin swab
consequtive mt417
preparation of pure cultures
sterilize loop, streak made over sterile agar plate, subsequent streaks made after resterilization. confluent growth at beginning, individual colonies at the end.
comparison of effects of the 2 mehods used for plating microorganisms
spread:sample plotted onto surface,spread evenly,incubation,colonies
pour:sample pipetted, add sterile medium, incubation, surface and subsurface colonies
enumerating cells in samples and cultures
suspended in liquids, direct and viable counts.
direct or total cell counts
1.count under microscope,slow
2.turbidity:photo/spectrophotometer
3.electronic:coulter,particle sizer
advantages
disadvantages
1.quick, useful
2.cant distinguish dead from viable, look-alikes
petroff-hausser chamber
add sample with no overflow, all cells counted in large square.
1mm^3=1ul
1ml=10e3ul
photometer
spectrophotometer
filter/prism-(incident light)
sample w/ cells (unscattered)
photocell:measures
recorder/units
enumerating cells in samples and cultures
(viable cell or colony counts)
viable:assumption every live cell with grow and generate.
advantages:distinguish diff organisms, assess contaminants in food/h2o
disadv:elaborate prep, labor intensive, not all will grow
enumerating viable cells in suspensions and cultures
assess bacteria in foods, water, clinical samples, industrial processes.....
serial
pour/spread
incubation
colony count
calc of viable cells
great plate count anomaly
counts usually underestimate the number of viable microbial cells in food, water, feces, soil, swabs from skin and body orifices, by one to serveral orders of magnitudes.