Term
| who discovered restriction enzymes? |
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Definition
| Swiss microbiologist Werner Arber and Stuart Linn |
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Term
| what did Werner Arber's daughter Sylvia call restriction enzymes? |
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Definition
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Term
| Arber discovered restriction enzymes while... |
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Definition
| studying a phenomenon known as host-controlled restriction of bacteriophages (also known at the time as host-controlled modification of bacteriophages). |
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Term
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Definition
| viral particles that invade bacteria and replicate their own DNA independently of the bacterial chromosomal DNA |
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Term
| the basis for Arber discovering restriction enzymes |
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Definition
| he wanted to know why bacterial phages did better in some strains of bacteria than others |
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Term
| what Arber proposed before discovering restriction enzymes |
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Definition
he theorized that previous exposure to a particular bacterial strain somehow protected that phage from that bacterial strain
Arber also proposed that there were specific sites in the virus with unmodified genome where restriction occured |
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Term
| Arber and Linn referred to the enzyme responsible for this "endonucleolytic scission" as... |
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Definition
| endonuclease R, a name later changed to EcoB |
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Term
| a restriction enzyme discovered in E. coli after Arber and Linn's research |
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Definition
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Term
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Definition
| enzyme discovered in another bacterial species that degrades foreign phage DNA but not the bacterial host's DNA |
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Term
| restriction or recognition site |
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Definition
| the actual nucleotide sequence of the specific site where a restriction enzyme cleaves |
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Term
| significance of discovering restriction or recognition site |
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Definition
| confirms Arber's hypothesis that restriction enzymes are extremely selective with regard to where they make their cuts |
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Term
| how many restriction enzymes are there? |
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Definition
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Term
| how many restriction sites are there? |
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Definition
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Term
| length of restriction sites |
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Definition
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Term
| most restriction sites are palindromic, meaning... |
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Definition
| the sequence reads the same forward and backward |
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Term
| how bacterial enzymes are named |
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Definition
| first 3 letters of bacterium from which it was isolated, e.g., Eco for E. coli, fourth letter for particular strain, e.g., EcoB, and Roman neumerals for enzymes from the same strain, e.g., EcoBII |
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Term
| the 3 categories of restriction enzymes recognized today |
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Definition
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Term
| type I restriction enzymes |
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Definition
| they recognize specific DNA sequences but make their cut at seemingly random sites that can be as far as 1,000 base pairs away from the recognition site |
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Term
| type II restriction enzymes |
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Definition
| they recognize and cut directly within the recognition site |
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Term
| type III restriction enzymes |
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Definition
| they recognize specific sequences but make their cut at a different specific location that is usually within about 25 base pairs of the recognition site |
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Term
| purpose of restriction enzymes |
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Definition
| defense against invading viruses |
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Term
| how bacteria protect their DNA |
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Definition
| by modifying their own recognition sequences |
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Term
| how bacteria modify their own recognition sequences |
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Definition
| usually by adding methyl (CH3) molecules to nucleotides in the recognition sequences and then relying on the restriction enzymes' capacity to recognize and cleave only unmethylated recognition sequences |
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Term
| how bacteriophages protect theirselves from restriction enzymes |
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Definition
| bacteriophages that have previously replicated in a particular host bacterial strain and survived are similarly modified with methyl-labeled nucleotides and thereby protected from cleavage within that same strain |
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Term
| the first major application of restriction enzymes |
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Definition
| as a tool for cutting DNA into fragments in ways that would make it easier to study and, in particular, identify and characterize genes |
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Term
| a second major use for restriction enzymes |
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Definition
| as a device for recombining, or joining, DNA molecules from different genomes |
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Term
| the goal of recombining, or joining, DNA molecules from different genomes |
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Definition
| identifying and characterizing a gene or studying gene expression and regulation |
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Term
| how scientists today separate DNA fragments |
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Definition
| restriction enzyme digestion, followed by electrophoresis |
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Term
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Definition
| a DNA or RNA molecule with a base sequence that is complementary to a DNA sequence of interest |
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Term
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Definition
| to identify where in the genome (i.e., on which fragment) the sequence of interest is located |
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Term
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Definition
1: DNA fragments electrophoretically separated
2: fragments transferred from gel to solid medium, or membrane |
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Term
| what is done to the DNA fragments after Southern blotting? |
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Definition
3: probes are used to bind to the sequences of interest
4: membrane is washed to leave only the probes bound to the membrane |
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Term
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Definition
| technique used to detect radioactive probes after the membrane is washed |
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Term
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Definition
| DNA fragments with no sticky ends |
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Term
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Definition
| overhanging single strands of DNA on a DNA fragment |
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Term
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Definition
| enzyme that can covalently bind complementary sticky-end fragments |
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Term
| what the utilization of sticky ends and DNA ligase enables molecular biologists to do |
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Definition
| create seemingly limitless combinations of recombinant DNA |
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