Aside from the diamond, the ruby, sapphire, emerald, pearl (not, strictly speaking, a gemstone) and opal have also been considered to be precious. Up to the discoveries of bulk amethyst in Brazil in the 19th century, amethyst was considered a precious stone as well, going back to ancient Greece.
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.ased on the sizes of the resultant DNA fragments the positions of the sites can be inferred. Restriction mapping is a very useful technique when used for determining the orientation of an insert in a cloning vector, by mapping the position of an off-center restriction site in the insert (Dale, Von Schantz, 2003).
The animation below tells you that restriction endonucleases are very useful to molecular biologists. They cut DNA at specific locations and can be used to look for genetic diversity, to cut up DNA into smaller pieces, and/or to splice DNA from different sources into one molecule.In cells restriction endonucleases are used to cut up invading DNA from viruses. The restriction sites are ones found in viral DNA.he animation below tells you that restriction endonucleases are very useful to molecular biologists. They cut DNA at specific locations and can be used to look for genetic diversity, to cut up DNA into smaller pieces, and/or to splice DNA from different sources into one molecule.