BI323 Final Exam Material from Exam 2 Flashcards
Which process are these a part of? elongation, replication, distribution, septum
binary fission
division of cytoplasm to form basal cell and larger apical cell
baeocyte formation
other strategies of reproduction in prokaryotes
spore formulation, budding
which parts are found in the chromosome replication of E. coli?
origin of replication and terminus found on the chromosome, and a replisome
what is partitioning
not well understood, role of MreB in cell shape and association of chromosomes
single copy plasmid R1 replicates, ParM is anchored to ParC and ParR which attach to the origin of each plasmid, ParM elongates pushing the plasmid to opposite poles of the dividing cell, newly replicated cells with plasmid, Par proteins not synthesized until the cell readies for division
plasmid partioning
involves septation, wall formation between daughter cells
steps: selection of site MinCDE, Z ring assembly (FtsZ), formation of divisome (Z ring linkage, assembly of machinery for cell wall synthesis, Z ring constriction)
cytokinesis
what type of cell growth do cocci/rods go through?
peptidoglycan synthesis through autolysins
used to maintain osmotic pressure
ex. choline, proline, glutamic acid
compatible solute
measure of water availability to organisms related to the concentration of solutes
water activity
organisms exhibit distinct _________ temperatures, which include?
cardinal growth, minimal maximal and optimal
what is the order of -philes from low Celsius to high?
psychrophiles, psychrotrophs, mesophiles, thermophiles, hyperthermophiles
their membranes contain unsaturated fatty acids
psychrophiles
protein structure stabilization through increasing H bonds, more proline, chaperones, DNA stabilization through histone like proteins, lipid stabilization with more saturated branches and higher MW, ester linkages in archaeal
thermophiles
what are these enzymes used for? superoxide dismutase, catalase, peroxidase
protective enzymes for oxygen concentration
how are barophilic (piezophillic) organisms adapted to pressure changes?
shorter, increased unsaturated fatty acids
x rays and gamma rays, disrupting chemical structures of DNA
ionizing radiation
formation of thymine dimers, DNA repair mechanisms through photoreactivation (dimers split in light presence) and dark reactivation (dimers replaced)
UV radiation
in high intensities, generates singlet oxygen which is a powerful oxidizing agent
carotenoids protect from photooxidation
visible light
total biomass of organism determined by nutrient present at lowest concentration
liebig’s law of the minimum
above or below certain environmental limits, a microorganism will not grow regardless of the nutrient supply
shelford’s law of tolerance
what are some responses to oligotrophic environments
increased competition, mechanisms to sequester certain nutrients, morphological changes that increase surface area nutrient absorption
quorum sensing in gm (-) bacteria, give some process examples
N-acyl homoserine lactone production
processes: bioluminescence, synthesis and release of virulence factors, conjugation, antibiotic production, biofilm production
quorum sensing in gm (+) bacteria, give some process examples
often mediated by oligopeptides
processes: transformation competence, sporulation, production of virulence factors, development of aerial mycelia, antibiotic production
controlled growth environment that can be used for certain bacteria
defined/synthetic media
contain some ingredients of unknown composition or concentration, can be used for many bacteria
components: peptones (hydrolysates from partial digestion), extracts( beef or yeast), agar (sulfated polysaccharide)
complex
favors growth of some microorganisms while inhibiting others ex. macconkey agar selects gm (-)
selective media
distinguish between different groups of microorganimss based on their biological characteristics ex. blood agar (homolytic vs non) ex. macconkey agar (lactose fermenters vs non)
differential media
what are some common techniques for the isolation of pure cultures?
spread plate, streak plate, pour plate
what are the characteristics used to identify colony morphology
form, elevation, margin
growth is most rapid at _______ because why?
colony edge, availability of O2 and nutrients
growth curves are observed in__________ which is incubated in a closed vessel
batch culture
which stage does unbalanced growth occur? what is this?
exponential phase, change in nutrient levels, leads to shift up or shift down
what are some starvation responses found in stationary phase?
morphological changes (decreased size, protoplast shrinkage, nucleoid condensation), production of starvation proteins, long term survival, increased virulence
what is mean growth rate (µ)
the number of generations per hour
mean generation (doubling) time
time required for the population to double in size
what are two ways to perform direct cell counts?
counting chambers and electronic counters
what are two ways to perform viable cell counts?
spread plating and membrane filtration methods
a method of direct cell count, hemacytometer which is easy, rapid and inexpensive
petroff hausser chamber
a method of direct cell count, cell suspension forced through small orifice that disrupts the current but can’t distinguish between living and dead
coulter counter
a method of direct cell count that uses a laser to scatter light and quantify
flow cytometry
a method of viable cell counts that determines the population size as CFU
spread plating
a method of viable cell counts that stains for easier visualization using fluorescent dyes to tell between living and dead cells
membrane filter
what are three ways of measuring cell mass
determination of dry weight (time consuming), quantity of particular cell constituent, turbidometric measurement (light scattering)
rate of incoming culture = rate if medium + cell removal, used when the quantity of an essential nutrient is limited, determined by rate of flow or dilution rate
chemostat
a chemostat best operates at _____ dilution levels
low
elimination of all microorganisms including spores
sterilization
the killing, inhibition or removal of pathogens but not necessarily sterilizing
disinfection
reduction to safe levels per public health standards
sanitation
prevention of infection of living tissue
antisepsis
dead organisms….
unable to reproduce under normal conditions and are VBNC (viable but not culturable)
what are the pore measurements of membrane filters?
0.2 micrometers and 0.45 micrometers, N95 0.3
autoclave degrades nucleic acids, denatures proteins and disrupts membranes
moist heat
less effective because it requires high temperatures and longer exposures, oxidizes cell constituents and denatures proteins
dry heat sterilization
what are the approximate conditions to heat kill bacteria
10 min at 60-70 celsius
what are the approximate conditions for heat killing viruses
30 min at 60 celsius
old pasteurization of milk…… new…….
63 celsius for 30 min, flash (HTST) 72 celsius for 15 sec, UHT 140-150 celsius for 1-3 seconds
decimal reduction time (D)
time to kill 90% of microorganisms and spores at a specific temperature
z value
increase in temperature required to reduce D by 1/10
surface sterilization that doesn’t penetrate, kills microorganims and inactivated viruses via thymine dimers
UV radiation
how is ionizing radiation used to kill
via gamma rays that penetrate deep, destroying cells and endospores but not always viruses (food sterilization)
first antiseptic common in labs and hospitals, denatures proteins and disrupts cell membranes, odor and skin irritation
phenol
what are alcohols used for
bactericidal, fungicidal but not sporicidal and inactivates some viruses, denatures proteins and dissolves membrane lipids
oxidizes cell constituents and iodinates proteins, may kill spores, skin damage staining and allergies
iodine
iodine and organic carrier, water soluble and non-staining ex. wescodyne and betadine
iodophor
used to sterilize heat sensitive materials such as sutures and catheters, microbicidal and sporicidal and combine w/inactivate proteins, penetrating packing materials
sterilizing gases
conditions that influence antimicrobial effectiveness
- population size 2. population composition (spores and sensitivity) 3. concentration and intensity (EtOH 95% causes dehydration but then the microbes can be brought back after rehydration) 4. exposure duration 5. temperature 6. local environment
biological control of microorganisms
bacterial predators (bdellovibro gm (-) enters periplasm and eats host, bacteriophage therapy, bacteriocins
ability of drug to kill or inhibit pathogen while damaging host as little as possible
selective toxicity
drug level required for clinical treatment
therapeutic dose
drug level at which drug becomes too toxic for patient, creating side effects
toxic dose
comparison of toxic dose to therapeutic dose
therapeutic index
what are some of antibiotic’s mechanisms of action
- inhibitors of cell wall synthesis 2. protein synthesis inhibitors 3. metabolic antagonists 4. nucleic acid synthesis inhibitors
-beta lactam ring essential for bioactivity, many resistant organisms produce beta lactamase (penicillinase) which hydrolyzes a bond in the ring
- blocks enzyme that catalyzes transpeptidation
- only acts on growing bacteria synthesizing new peptidoglycan
penicillins
factors influencing drug effectiveness
- ability to reach site (venal, parenteral, topical, oral) 2. susceptibility of pathogen to drug 3. ability to reach and exceed MIC (amount, route, speed of uptake, rate of clearance) 4. acquired resistance
what are some mechanisms of acquired resistance
HGT, drug inactivation, target modification, reduce concentration of the drug, use if alternative metabolic pathway
optimal pH of 0-5.5
acidophiles
optimal pH of 5.5-8.0
neutrophiles
optimal pH of 8.0-11.5
alkalophiles
grow at 0-35C
psychrotrophs
grow at 0-20C
psychrophiles
grow at 20-45C
mesophiles
grow at 85-100C
hyperthermophiles
grow at 45-85C
thermophiles
requires oxygen and have + enzyme content for SOD and catalase
obligate aerobe
prefers oxygen and have + enzyme content for SOD and catalase
facultative anaerobe
ignores oxygen and had + enzyme content for SOD but not catalase
aerotolerant anaerobe
oxygen is toxic and does not have enzyme content for SOD and catalase
strict anaerobe
oxygen is required in 2-10% and had + enzyme content for SOD and catalase at low levels
microaerophile
