Exam I – Microbiology – Flashcards

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Prokaryote shapes
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Bacillus (Rod)
Coccus (Spherical)
Spirillum (Twisted or curved rod)
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Strepto-
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Chain of bacteria
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Staph-
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Cluster of bacteria
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Pleomorphic
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Bacteria that are variable in shape
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Surface-to Volume Ratios/Growth Rates
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Small cells have adavantage relative to cell volume. They need less nutrients to successfully provide for the whole cell
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Prokaryotic cytoplasm
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Contains Nucleoid, ribosomes, inclusion bodies, and spores
Composed of water and dissolved solutes
Site of cell functions
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Bacterial Cytoplasmic Membrane
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Polar, hydrophilic head
Nonpolar, hydrophobic tail
Amphipathic phospholipid bilayer
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Archael Cytoplasmic Membrane
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Ether linkages (instead of ester) in phospholipids
Lipids lack fatty acids
Major lipids are diethers and tetraethers
Monolayer or Bilayer
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Simple transport
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ATP or pmf for energy
Moves molecules against the concentration gradient
Involves carrier proteins
Uptake of organic compounds
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Group translocation
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Chemical modifies molecule as it's brought into cell
Sugar phosphotransferase system
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Phosphotransferase system
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Transports sugars while phosphorylating them using PEP as the phosphate donor
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ABC transporters
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ATP-Binding-Cassette
In bacteria, archaea, and eukaryotes
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Enzyme
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Protein catalyst that accelerates cellular chemical reactions
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Transcription
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DNA produces RNA
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Translation
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RNA makes protein
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Robert Hooke
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Viewed cork slices under early microscope describing "cella"
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Anton van Leeuwenhoek
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Made microscope with 300x magnification
First to view "animalcules" (Bacteria)
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Francesco Redi
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Meat in jar experiment disputing spontaneous generation
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Louis Pasteur
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Germ Theory
Rabies vaccination
Protection from cholera
Protection from anthrax
Pasteurization
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Robert Koch
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Proved Germ Theory
Koch's postulates
Pure culture technique
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Eukaryotic Microorganisms
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Fungi, Protozoa, Algae, Slime molds
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Prokaryotic Microorganisms
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Bacteria and Archaea
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Phototrophs
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Use light as energy source
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Chemolithotrophs
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Inorganic Chemicals as Energy Source
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Chemoorganotrophs
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Organic molecules as energy source
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Domain Bacteria
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All known pathogenic prokaryotes
Proteobacteria is largest phylum
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Proteobacteria
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All gram negative
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Archaea Phylums
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Euryarchaeota
Crenarchaeota
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Euryarchaeota
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Methanogens: degrade organic matter anaerobicall producing methane
Extreme Halophiles: require high salt concentrations
Thermoacidophiles: High temperatures and low pH
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Crenarchaeota
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Hyperthermophiles
Live in marine, freshwater, or soil
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Uniporter
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Simple transport involving the absorption of individual molecules one at a time
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Antiporter
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Simple transport involving the absorption and removal of individual molecules at the same time
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Symporter
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Simple transport involving the absorption of multiple molecules at the same time
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Protein Export
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Translocation machinery moving proteins through and inserting into prokaryotic membranes
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Gram-positive cell wall
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One layer of membrane and one layer of peptidoglycan
Contains large amounts of teichoic acids
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Gram-negative cell wall
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Double layer membrane with peptidoglycan in the perplasmic space between membranes
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Periplasm
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Gel-like space that lies between membranes in Gram-negative bacteria
Contains high concentration of proteins
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Archaea Cell Walls
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No peptidoglycan, Pseudomurein instead
No outer membrane
Specialize for biological habitat
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Capsule
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Usually composed of polysaccharides and protein
Well organized
Not easily removed from the cell
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Slime Layer
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Diffusion
Unorganized
Easily Removed
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Functions of Capsules/Slime Layers
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Protection from host defenses (phagocytosis)
Protection from environment
Attachment to surfaces
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Fimbriae
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Shorter appendages
Mediate attachment to surfaces
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Pili
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Some required from twitching/gliding motility
Longer than fimbriae
Less numerous than fimbriae
Adheres pathogens to specific tissues
Required for conjugation
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Cell Inclusion Bodies
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Granules of organic or inorganic material stockpiled for future use
Some membrane bound
Aquatic bacteria use gas vesicles to float
Magnetostomes contain magnetite or greigite allowing response to magnetic fields
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Endospores
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Usually formed by Gram-positive bacteria
Dormant and highly resistant to environmental conditions
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Reasons for Endospore Resistance
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Spore coat
DNA repair enzymes present
Dehydrate core
Small acid-soluble, DNA-binding proteins
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Sporogensis
(Sporulation, Endospore Formation)
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Starts when growth ceases due to lack of nutrients
Complex, multistage process
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Dormant spore to Active Vegetative Cell Process
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Activation
Germination
Outgrowth
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Flagella
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Long appendages for motility
Contain helical filament, hook, and basal body
Rotation propels cell
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Polar flagella distribution
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Flagellum at end of cell
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Monotrichous Flagella Distribution
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One flagellum
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Amphitrichous Flagella Distribution
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One flagellum at each end
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Lophotrichous Flagella Distribution
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Cluster of flagella at one or both ends
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Preitrichous Flagella Distribution
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Flagellum spread over entire cell surface
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Flagellar Movement
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Counterclockwise causes forward motion (run)
Clockwise disrupts forward motion (tumble)
Powered by PMF in bacteria
Powered by ATP in archaea
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Microbial Taxis
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Directed movement in response to chemical or physical gradients
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Chemotaxis
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Movements toward or away from a chemical stimulus
Concentrations of chemical stimuli detected by chemoreceptors
In presence of chemical attractant, tumbling frequency is reduced
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Phototaxis
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Response to light
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Aerotaxis
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Response to oxygen
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Osmotaxis
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Response to ionic strength
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Hydrotaxis
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Response to water
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Microbial Nutrient Requirements
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In high amounts: C, O, H, N, S, P, K, Ca, Mg
In trace amounts: Fe, Mn, Zn, Co, Mo, Ni, Cu
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Growth Factors
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Essential cell components that the cell cannot synthesize
Must be supplied by environment for successful cellular life
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Classes of Growth Factors
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Amino acids
Purines and pyrimidines
Vitamins
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Photolithoautotroph
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Carbon Source: CO2
Energy Source: Light
Electron Source: Inorganic donor
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Photoorganoheterotroph
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Carbon Source: Organic carbon
Energy Source: Light
Electron Source: Organic donor
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Chemolithoautotroph
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Carbon Source: CO2
Energy Source: Inorganic chemicals
Electron Source: Inorganic donor
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Chemoorganoheterotroph
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Carbon Source: Organic carbon
Energy Source: Same as carbon source
Electron Source: Same as carbon source
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Catabolism
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Energy conserving reaction that generates electrons
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Anabolism
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Synthesis of complex organic molecules from simpler ones
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Energy from redox reactions stored in
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ATP
Phsophenolpyruvate (PEP)
Glucose 6-phosphate
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Proton Motive Force (PMF)
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Protonse released during electron transfer
Result in electrochemical potential across the membrane
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ATP Synthase (ATPase)
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Converts PMF to ATP
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Microbial Growth Cycle
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Lag phase
Exponential Phase
Stationary Phase
Death Phase
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Possible Reasons for starting Stationary Phase
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Nutrient limitation
Limited O2 availability
Toxic waste accumulation
Critical population density reached
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Death Phase
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Apoptosis
Cells are viable but not culturable (VBNC)
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Microbial Growth Range
(Coldest to Hottest)
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Psychrophile
Mesophile
Thermophile
Hyperthermophile
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Thermophile Adaptations
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Protein and enzyme structures more heat stable
Solute production stabilizes proteins
Membrane stabilized by multiple means
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Acidophiles
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Growth optimum between pH 0-5.5
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Neutrophiles
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Optimum growth between pH 5.5-8
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Alkalophiles
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Optimum growth between pH 8-11.5
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Water Activity (aw)
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Amount of water available to organisms
Reduced by interaction with solute molecules
Reduced by adsorption to surfaces
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Osmophiles
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Organisms that live in environments high in sugar as solute
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Xerophiles
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Organisms able to grow in very dry environments
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Halophiles
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Optimum growth at ~3%
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Extreme Halophiles
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Require >15-30%
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Obligate Aerobes
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Dependent on atmospheric oxygen for growth
Growth only seen in oxygen rich areas of environment
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Obligate Anaerobes
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Die in presence of oxygen
Only present in anoxic areas of environment
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Facultative Aerobes
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Grow better in presence of oxygen, but do not require it
Uneven growth can be observed with more in oxygen rich area
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Microaerophiles
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Require lower than normal level of oxygen
Uneven growth observed with more growth in anoxic environment
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Aerotolerant Aerobe
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Ignore oxygen levels during growth
Uniform growth throughout entire environment
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