Uses of Restriction Enzymes

Uses of Restriction Enzymes

	Uses of Restriction Enzymes Restriction enzymes have been used for sequence analyses of DNA and for cloning and amplifying DNA. DNA from animal viruses bacteriophages contains from 5,000 to 50,000 base pairs. It is important to know the primary structure of DNA, i.e the sequence of bases, for decoding the information stored in genes and for understanding gene structure and regulation at molecular level. The discovery of restriction enzymes was a major breakthrough in sequence analysis of DNA. .
By using combinations of different restriction enzymes it is possible to hydrolyze large DNA molecules into fragments less than 300 base pairs in length These fragments can then be used for sequence analysis and arranged into a physical map of the chromosome. This is a slow and laborious process. The mapping of the entire 5,000 base pair DNA of the virus SV40 into some 100 fragments has taken several years. Complete sequence analysis of the fragments would take much longer. The DNA fragments produced by restriction endonucleases can be covalently linked in vitro to linear plasmid DNA or to lambda phage DNA.
The recombinant DNA species produced can be inserted into E.coli by transformation. Each transformed cell can then be grown as a separate clone. By this method a complex genome can be broken down into thousands or millions of pieces, and each piece isolated to form a separate clone.