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65 Cards in this Set
- Front
- Back
the increase in number of cells, not cell size
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microbial growth
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what is one physical requirement for growth
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temperature
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3 types of temperature
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minimum
optimum maximum |
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psychrotrops cause
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food spoilage
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most bacteria grow between pH
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6.5 and 7.5
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molds and yeasts grow between pH
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5 and 6
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acidophiles grow in
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acidic environments
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hyptertonic environments increase
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salt or sugar
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hypertonic environmnts cause
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plasmolysis
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extreme or obligate halophiles require
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high osmotic pressure
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facultative halophiles tolerate
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high osmotic pressure
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carbon: structural organic molecules use
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energy source
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chemoheterotrops use
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organic carbon sources
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autotrophs use
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CO2
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nitrogen is in
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amino acids and proteins
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some bacteria use
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NH4+ or NO3-
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a few bacteria use N2 in
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nitrogen fixation
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sulfur in amino acids is
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thiamine and biotin
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momost bacteria in both sulfur and nitrogen decompose
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proteins
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some bacteria use
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SO42- or H2S
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phosporus is in
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DNA, RNA, ATP, and membranes
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what is a source of phosphorus
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PO43-
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inorganic elements required in small amounts
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trace elements
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trace elements are usually as
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enzyme cofactors
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obligate aerobes
facultative anaerobes obligate anaerobes aerotolerant anaerobes micro-aerophiles |
types of oxygen (O2)
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singlet oxygen is toxic because
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02 boosted to a higher-energy state
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superoxide free radicals goes through
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superoxide dimultase
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peroxide anion goes through
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catalase
peroxide |
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toxic forms of oxygen
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singlet oxygen
hydroxyl radical |
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singlet oxygen types
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superoxide free radicals
peroxide anion |
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organic compounds are obtained from
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the environment
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what are some organic compounds
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vitamins, amino acids, purines, and pyrimidines
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nutrients prepared for microbial growth
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culture medium
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no living microbes
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sterile
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introduction of microbes into medium
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inoculum
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microbes growing in/on culture medium
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culture
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agar has complex
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polysaccharide
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what is used as a solidifying agent for culture media in
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Petri plates, slates, and deeps
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agar is generally not metabolized by
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microbes
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agar liquefies at
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100*C
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solidifies at
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-40*C
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exact chemical composition is known
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chemically defined media
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extracts and digests of yeast, meat or plants
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complex media
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types of complex media
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nutrient broth & agar
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reducing media contains chemicals that
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combine 02
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reducing media is heated to
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drive off 02
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heated to drive off 02
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anaerobic jar
anaerobic chamber |
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require high CO2
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capnophiles
candle jar Co2-packet |
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suppress unwanted microbes and encourage desired microbes
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selective media
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make it easy to distinguish colonies of different microbes
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differential media
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encourages growth of desired microbe
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enrichment media
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contains only one species or strain
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pure culture
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a population of cells arising from a single cell or spore or from a group of attached cells
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colony
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a colony is often called a
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colony-forming unit (CFU)
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deep-freezing
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-50*C to -95*C
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lyophilization
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freeze-drying
frozen (-54*C to-72*C) and deydrated in a vacuum |
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reproduction in prokaryotes
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binary fission
budding conidiospores fragmentation of filaments |
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perform serial dilutions of a sample
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plate counts
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inoculate Petri plates from
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serial dilutions
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after incubation
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count colones in plates that have 25-250 colonies
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direct measurements of microbial growth
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filtration
multiple tube MPN test direct microscope count capillary actions |
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count positive tubes and compare to statistical MPN table
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multiple tube MPN test
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how do you estimate bacterial numbers by indirect methods
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turbidity
#of bacteria-ml or # of cells counted / volume |
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direct methods of measuring microbial growth
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plate counts
filtration MPN direct microscopic count dry weight |
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indirect method of measuring microbial growth
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turbidity
metabolic activity dry weight |