Test Questions on Chapter 6 – Microbiology – Flashcards
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microbial growth |
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three things that all cells need for metabolism |
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autotrophs |
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heterotrophs |
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chemotrophs |
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organisms that acquire energy from redox reactions involving inorganic and organic chemicals |
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phototrophs |
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organisms that use light as their energy source |
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four basic groups of organisms based on their energy and carb sources: |
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limiting nutrient |
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organotrophs |
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(heterotrophs) acquire their electrons from the same organic molecules that provide them carbon |
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lithotrops |
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(autotrophs) acquire electrons or hydrogen atoms from inorganic molecules |
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obligate aerobes |
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obligate anaerobes |
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oxygen is a "deadly poison" for these organisms |
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four toxic forms of oxygen |
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singlet oxygen |
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superoxide radical |
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peroxide anion |
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hydroxyl radical |
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facultative anaerobes |
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aerotolerant anaerobes |
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microaerophiles |
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nitrogen (for growth requirements) |
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nitrogen fixation |
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phosphorus (for growth requirements) |
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component of phospholipid membranes, DNA, RNA, and some proteins |
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sulfur (for growth requirements) |
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lithotrophic photoautotrophs |
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growth factors |
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temperature (for growth requirements) |
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minimum growth temperature |
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the lowest temperature at which an organism is able to conduct metabolism |
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maximum growth temperature |
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highest temperature at which an organism continues to metabolize |
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optimum growth temperature |
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temperature at which an organism's metabolic activities produce the highest growth rate |
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psychrophiles |
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microorganisms which grow best at temperatures below 15*C |
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mesophiles |
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thermoduric organisms |
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mesophiles that can survive brief periods at higher temperatures |
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thermophiles |
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organisms which grow at temperatures above 45*C in habitats such as compost piles and hot springs |
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hyperthermophiles |
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usually archea, grow in water above 80*C, others live at temperatures above 100*C |
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pH growth requirements |
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organisms are sensitive to changes in acidity because hydrogen ions and hydroxyl ions interfere with hydrogen bonding within proteins and nucleic acids |
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neutrophiles |
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acidophiles |
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alkalinophiles |
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live in alkaline soils and water up to pH 11.5 |
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osmotic pressure |
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crenation |
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shriveling of a cell in a hypertonic environment |
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obligate halophiles |
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facultative halophiles |
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microbes that do not require high salt concentrations but can tolerate them |
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hydrostatic pressure |
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barophiles |
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antagonistic relationships |
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relationships in which one organism harms or kills another organism |
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synergistic relationships |
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individual members of an association cooperate such that each receives benefits that exceed those that would result if each lived by itself, even though each member could live separately |
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symbiotic relationships |
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organisms live in such close nutritional or physical contact that they became interdependent |
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biofilms |
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quorom sensing |
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process by which bacteria respond to changes in microbial density by utilizing signal and receptor molecules |
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inoculum |
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medium |
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collection of nutrients used for cultivating microorganisms |
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culture |
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colonies |
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cultures that are visible on the surface of solid media |
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clinical specimen |
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pure cultures |
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CFU's |
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defined medium |
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fastidious organisms |
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complex media |
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selective media |
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typically contain substances that either favor the growth of particular microorganisms or inhibit the growth of unwanted ones |
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differential media |
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formulated such that either the presence of visual changes of the medium or differences in the appearance of colonies help microbiologists differentiate among different kinds of bacteria growing on the medium |
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MacConkey agar |
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reducing media |
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transport media |
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media used by hospital personnel to carry clinical specimens of feces, urine, saliva, sputum, blood, and other bodily fluids in such a way that people are not infected and the specimens are not contaminated |
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animal and cell culture |
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living tissue required to grow and cultivate specific types of microorganisms |
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carbon dioxide incubators |
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candle jar |
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capnophiles |
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microorganisms that grow best with high levels of carbon dioxide in addition to low levels of oxygen |
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enrichment culture |
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cold enrichment |
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refrigeration (for storage) |
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best technique for storing cultures for short periods of time |
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deep-freezing |
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lyophilization |
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binary fission |
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binary fission steps |
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logarithmic growth |
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generation time |
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growth curve |
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a graph that plots the number of organisms in a growing population over time |
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semilogarithmic graph |
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only one axis uses a log scale |
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lag phase |
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log phase |
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stationary phase |
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death phase |
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chemostat |
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serial dilution |
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a stepwise dilution of a liquid culture in which the dilution factor at each step is constant |
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viable plate count |
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membrane filtration |
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most probable number (MPN) |
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Petroff-Hausser counting chamber |
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Coulter counter |
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metabolic activity |
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dry weight |
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turbidity |
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genetic methods |
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scientists can isolate unique DNA sequences representing unculturable prokaryotic species using genetic techniques such as polymerase chain reaction (PCR) and hybridization of DNA that codes for ribosomal RNA |