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).
Scientists can also use restriction enzymes to map plasmids, through a process called restriction mapping. A plasmid is a section of bacterial DNA that isn't included in the larger genome, or DNA sequence.Bacteria can pass plasmids back and forth, which spreads genes within a bacterial population.pecifically, bacteria use restriction enzymes to cut DNA at specific sites. This is useful to the bacteria for protecting against infection, but scientists can also take advantage of the function of a restriction enzyme and there are many different uses for restriction enzymes both by bacteria and in the lab.