Term
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Definition
| double stranded, circular DNA fragment that is extrachromosomal to actual DNA and undergoes autonomous replication in bacteria |
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Term
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Definition
genetic element that alternates between an autonomous state and a state in which it is integrated into the chromosome *not all plasmids are episomes
*when in DNA, under replication control of DNA |
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Term
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Definition
| transferable genetic element, often used interchangably with both plasmid and episome |
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Term
| Where are linear plasmids found? |
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Definition
| Borrelia and Streptomyces |
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Term
| Methods of plasmid transfer |
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Definition
| conjugation (these plasmids have genes encoding sex pili in gram negative or sex pheromones and adhesins in gram positive), transduction, transformation |
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Term
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Definition
| genes on large plasmids which encode all functions required for replication (especially F factor) |
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Term
| When does one suspect a plasmid? |
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Definition
*simultaneous, multiple drug resistance
*pattern of resistance found in multiple species, and when it exists in multiple individuals with a common contact |
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Term
| Laboratory proof of plasmid existence |
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Definition
1. Biochemical isolation
2. Genetic transfer
3. Curability of cell via UV, acridine, etc. |
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Term
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Definition
Large, self-replicating (conjugative) plasmids that confer drug resistance and are widely distributed among enterobacteria and other gram negative bacteria
*one portion for transferability, another portion for drug resistance
*most common cause of acquired drug resistance
*readily transfer between different species of gram negative bacteria |
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Term
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Definition
| Resistance Transfer Factor; like tra gene of F factor, region of an R-factor that contains all the genes for transferability of the R-factor |
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Term
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Definition
| portion of R-factor that encodes genes for drug resistance in gram negative bacteria |
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Term
| what antibiotics are responsible for the creation of R-factors |
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Definition
| none; the presence of R-factors predates the advent of antibioitics. antibiotics are responsible for selecting for certain R-factors, not for their creation |
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Term
| in what bacteria are R factors frequently found? |
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Definition
| Enterobacteriaceae and Bacteroides |
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Term
| Which Gram positive genera harbor plasmids carrign antibiotic resistance? |
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Definition
| Bacillus, Streptococcus ,Staphylococcus, Streptomyces, and Clostridium |
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Term
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Definition
| protein induced by pheromone of plasmid-receptor gram positive bacteria that grows on plasmid donor, connecting the donor and recepient cells |
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Term
| Nomadic DNA Sequences/Transposable Elements |
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Definition
| specific DNA sequences that insert into multiple sites in the chromosome or plasmids, and can move to new positions in the genome independent of DNA homology (IS elements and Transposons) |
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Term
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Definition
| 800-1400 bp, with transposase gene, four common elements in E. coli (1,2,3,4), insertion into a gene often inactivates the gene; insert at numerous sites in E.coli genome independently of DNA sequence homology |
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Term
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Definition
2000 bp, code for transposase (IS element) plus other genes that could include ab resistance, enterotoxins, etc.
*identified by loss of gene function plus ab resistance |
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Term
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Definition
| Transposon with transposase, b-lactamase and transposase receptor |
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Term
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Definition
| most complicated transposon ,carries an entire phage genome on it; inserts in DNA at random causing mutations |
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Term
| what are the two genetic roles of transposable elements? |
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Definition
1. gene expression: Tn has transcription promoters, terminators, nonsense codons, so it basically acts as a gene switch
2. Gene evoluton: blocks of genes become rearanged through transpositions, deletions, etc. Deletions adjacent to transposons occur at 100 to 1000 fold higher rates than at other sites |
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Term
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Definition
| plasmids encoding proteins that are involved in the pathogenic properties of a bacteria (tetanus toxin of clostridum tetani, anthrax, enterotoxins of e.coli) |
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Term
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Definition
| plasmids that carry bacteriocin, which kills or inhibits bacteria from growing; some large ones are self-conjugating some small ones aren't; sometimes acquire and carry drug resistant genes |
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