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15 Cards in this Set
- Front
- Back
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adaptation hypothesis
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implies that the interaction of the phage and bacterium is essential to the acquisition of immunity. In other words, exposure to the phage “induces” resistance in the bacteria.
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spontaneous mutation
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A mutation that is not induced by a mutagenic agent.
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fluctuation test
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A statistical test developed by Salvadore Luria and Max Delbrück that demonstrated that bacterial mutations arise spontaneously, in contrast to being induced by selective agents.
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T/F: Spontaneous mutation is now considered the primary source of genetic variation in bacteria.
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True.
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Selection refers to....
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growing the organism under conditions where only the desired mutant grows well, while the wild type does not grow. With carefully designed selection, mutations for almost any desired characteristic can now be isolated
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minimal medium
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A medium containing only the essential nutrients needed to support the growth and reproduction of wild-type strains of an organism. Usually comprised of inorganic components that include a carbon and nitrogen source.
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prototroph
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A strain (usually of a microorganism) that is capable of growth on a defined, minimal medium. Wild-type strains are usually regarded as prototrophs and contrasted with auxotrophs.
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auxotroph
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A mutant microorganism or cell line that requires a nutritional substance for growth that can be synthesized, and is not required by the wild-type strain.
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bacterium that loses the ability to make histidine is designated as.....
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his − auxotroph, in contrast to its prototrophic his + counterpart. For the his− bacterium to grow, this amino acid must be added as a supplement to the minimal medium.
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complete medium.
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Medium that has been extensively supplemented
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lag phase
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initial phase where bacterial growth is slow
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logarithmic (log) phase
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a period of rapid growth when cells divide continually with a fixed time interval between cell divisions, resulting in exponential growth.
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stationary phase
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phase when nutrients are exhausted and cells cease dividing. Usually when a cell density of about 109 cells/mL of culture medium is reached.
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conjugation
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Temporary fusion of two single-celled organisms for the sexual a process by which genetic information from one bacterium is transferred to and recombined with that of another bacterium.
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genetic recombination
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as applied to bacteria and bacteriophages, refers to the replacement of one or more genes present in one strain with those from a genetically distinct strain. Provided the basis for the development of chromosome mapping methodology.
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