A plasmid, most commonly found as circular and double-stranded DNA, is a small DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. In nature, plasmids carry genes that may benefit the survival of the organism (e.g. antibiotic resistance). You are given the following plasmids and bacteria: Plasmid A has an ampicillin-resistant gene (AmpR). Plasmid B has a kanamycin-resistant gene (KanR). Bacteria X contains plasmid A. Bacteria Y contains plasmid B. Bacteria Z contains both plasmids A and B. Which of the bacteria can grow on the plate containing no antibiotics? Which of the bacteria can grow on the plate containing kanamycin?
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Extract the plasmids from the bacteria. Show more…
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Plasmids are circular pieces of double-stranded DNA. However, in class, we will be working with a linearized plasmid. Choose the best possible answer that makes both previous statements possible. a) Plasmids can naturally exist as both linear and circular; the scientist has to choose the plasmid that fits their needs. b) Plasmids are naturally occurring circular-double stranded DNA molecules but can be made linear with the use of exonucleases (this answer is incorrect). c) Plasmids are naturally occurring double-stranded DNA molecules; they cannot exist as linear DNA or they would quickly get degraded. d) Plasmids are naturally occurring circular double-stranded DNA molecules but can be made linear with the use of endonucleases. e) Plasmids are naturally occurring circular double-stranded DNA molecules but can become linear via spontaneous reactions.
Shveta P.
A plasmid has the antibiotic resistance genes for kanamycin and ampicillin. You insert foreign DNA into the ampicillin resistance gene. E. coli containing the recombinant plasmid (plasmid + foreign DNA) will grow in the presence of ampicillin but not in the presence of kanamycin. A) True B) False 2. Expression of a gene could result in... A) transcription of mRNA from the gene B) transcription of a protein from the gene C) translation of the DNA of the gene 3. Restriction enzymes like EcoRI are endonucleases. An endonuclease will... A) Break glycosidic bonds B) Break a phosphodiester bond only at the 3' or 5' end of DNA C) Break a phosphodiester bond in the interior of a polynucleotide but not at the ends.
Adi S.
A plasmid is a small circular piece of DNA. Plasmids have restriction sites and usually carry a specific gene - often an antibiotic resistance gene. Since they are small, one restriction enzyme will usually only find one site for its specific cutting capabilities. The name of a plasmid contains the gene which it carries preceded by a "p": for example, pAMP is the name for the plasmid that contains the gene for ampicillin resistance. Following is the plasmid map for pAMP. Notice that the map contains the location of the gene, the position of the origin (which is the spot at which replication begins), the names of the restriction enzymes, and their restriction sites designated by the base pair distance. Therefore, from a plasmid map, a research scientist can determine which enzymes can most effectively be used to cut out the gene in order to transfer that gene to another plasmid. The scientist must be careful that ALL of the gene is removed but does not want unnecessary amounts of plasmid DNA. After viewing the plasmid, determine which enzymes would be best for cutting the ampicillin gene out of pKAN. In addition, determine the size in number of base pairs of the cut piece of plasmid.
Michelle M.
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