Restriction Enzymes

A restriction enzyme (or restriction endonuclease) is an enzyme that cuts double-stranded DNA. The enzyme makes two incisions, one through each of the sugar-phosphate backbones (i.e., each strand) of the double helix without damaging the nitrogenous bases. The chemical bonds that the enzymes cleave can be reformed by other enzymes known as ligases, so that restriction fragments carved from different chromosomes or genes can be spliced together, provided their ends are complementary (more below). Many of the procedures of molecular biology and genetic engineering rely on restriction enzymes. The term restriction comes from the fact that these enzymes were discovered in E. coli strains that appeared to be restricting the infection by certain bacteriophages. Restriction enzymes therefore are believed to be a mechanism evolved by bacteria to resist viral attack and to help in the removal of viral sequences. They are part of what is called the restriction modification system. The 1978 Nobel Prize in Medicine was awarded to Daniel Nathans and Hamilton Smith for the discovery of restriction endonucleases, leading to the development of recombinant DNA technology. The first practical use of their work was the manipulation of E. coli bacteria to produce human insulin for diabetics. This movie is made by Dr Nguyen Thanh Cong working at the Agricultural Genetics Institute in Hanoi, VIETNAMAddress below:Dr Nguyen Thanh CongMolecular Biology LaboratoryAgricultural Genetics InstituteVien Di truyen Nong NghiepTuliem, HanoiVIETNAM

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Channels: Scientific Animations Biochemistry Genetics

Tags: restriction

Uploaded by: ( Send Message ) on 08-09-2007.

Duration: 0m 47s