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A restriction map is a map of known restriction sites within a sequence of DNA. Restriction mapping requires the use of restriction enzymes . In molecular biology , restriction maps are used as a reference to engineer plasmids or other relatively short pieces of DNA, and sometimes for longer genomic DNA.
One bacterial plasmid used in genetic engineering as a plasmid cloning vector is pUC18. Its polylinker region is composed of several restriction enzyme recognition sites, that have been engineered into a single cluster (the polylinker). It has restriction sites for various restriction enzymes, including EcoRI, BamHI, and PstI.
Long-range restriction mapping is an alternative genomic mapping technique to short-range, also called fine-scale mapping. Both forms utilize restriction enzymes in order to decipher the previously unknown order of DNA segments; the main difference between the two being the amount of DNA that comprises the final map. The unknown DNA is broken ...
Optical mapping [1] is a technique for constructing ordered, genome-wide, high-resolution restriction maps from single, stained molecules of DNA, called "optical maps". By mapping the location of restriction enzyme sites along the unknown DNA of an organism, the spectrum of resulting DNA fragments collectively serves as a unique "fingerprint" or "barcode" for that sequence.
Molecular biology tools. Vector Database—A curated list of over 4,000 vector backbones, including relevant cloning information and bacterial growth conditions.. Sequence Analyzer—An Addgene software tool for creating plasmid maps from sequences with annotated features and restriction sites.
Several databases exist for restriction sites and enzymes, of which the largest noncommercial database is REBASE. [5] [6] Recently, it has been shown that statistically significant nullomers (i.e. short absent motifs which are highly expected to exist) in virus genomes are restriction sites indicating that viruses have probably got rid of these motifs to facilitate invasion of bacterial hosts. [7]
The classical restriction enzymes cut up, and hence render harmless, any unknown (non-cellular) DNA that enters a bacterial cell as a result of a viral infection. They recognize a specific DNA sequence, usually short (3 to 8 bp), and cut it, producing either blunt or overhung ends, either at or nearby the recognition site.
Molecular cloning takes advantage of the fact that the chemical structure of DNA is fundamentally the same in all living organisms. Therefore, if any segment of DNA from any organism is inserted into a DNA segment containing the molecular sequences required for DNA replication, and the resulting recombinant DNA is introduced into the organism from which the replication sequences were obtained ...