Restriction enzymes cutting

Fig. 2. (a) Map of pUC19, a commonly used plasmid vector where the numbers correspond to the positions of the various restriction enzyme cuts and (b) nucleic acid composition of pUC19 from position 393 (5 -end) through position 469 (3 -end) (5,7). 

Marker Known location on a chromosome (e.g., restriction enzyme cutting site, gene) whose inheritance can be monitored. Markers are located in or close to coding regions of DNA (i.e., genes) or in segments of DNA with no known coding function but whose pattern of inheritance can be determined (i.e., microsatellites). 

Most useful restriction enzymes cut DNA at specific recognition sites, usually four to six nucleotides in length. There can be multiple restriction sites for a single endonuclease within a given piece of DNA, there can be only one (a unique restriction site), or there can be none. It all depends on the sequence of the specific piece of DNA in question. 

By contrast, other restriction enzymes cut at different portions of a DNA molecule, forming an "offset" break with "sticky" ends. For example, the restriction enzyme known as BamHI cuts between two GG nitrogen bases, but at different parts of the DNA molecule, forming "overhangs or sticky ends. These sticky ends provide locations at which new nitrogen base sequences can be inserted. 

Map maps a DNA sequence, displaying restriction enzyme cut points and protein translations. 

One of the most important developments in the recent history of biochemistry is the discovery of restriction endonucleases (also called restriction enzymes). Restriction endonucleases are enzymes that catalyze the double-strand cleavage of DNA at specific base sequences. That is, restriction enzymes cut DNA strands at specific DNA sequences, generating fragments of specific sizes that can be separated and visualized on gel electrophoresis (Figure 25.6). 

Most restriction enzymes cut DNA in a way that leaves sticky ends that are very useful for recombining DNA from different sources. 

DNA and RNA can be radiolabeled with carbon-14,hydrogen-3,or phosphorus-32 and then separated into their constituent nucleotide sequences by enzymatic digestion. Restriction enzymes cut double-stranded DNA through each of the sugar-phosphate backbones, without damaging the nucleotide bases. 

Johnston APR, Lee L, Wang Y, et al. (2009) Controlled degradation of DNA capsules with engineered restriction-enzyme cut sites. Small 5 1418-1421... 

An important step in the development of techniques allowing such a molecular analysis of large regions in mammalian genomes has been the identification of restriction enzymes cutting rarely in mammalian DNA, and therefore able to cleave the mammalian genome into specific fragments of hundreds to thousands of kilo-base pairs. 

Beyond the specificity and predictability of DNA, nature has provided a comprehensive tool box to manipulate DNA In fact, nature provides virtually every tool an engineer would need to build. Restriction enzymes cut DNA at specific sequences of bases. Ligase fuses the ends of two molecules. More complex sets of enzymes can be used to make virtually unlimited copies of a DNA molecule. Polymerase chain reaction technology uses DNA polymerases to exponentially copy DNA molecules. Enzymes... 

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