give a detailed view of CASPR9 an unimaginable invention
Answers
Answer:
The standard gene-editing tool, CRISPR-Cas9, frequently produces a type of DNA mutation that ordinary genetic analysis misses, claims new research published in the journal Science Advances. In describing these findings the researchers called such oversights “ serious pitfalls ” of gene-editing. In all, the new results suggest that gene-editing is more error-prone than thought and, further, that identifying and discarding defective and unwanted outcomes is not as easy as generally supposed.
GM hornless cow
Spotigy, transgenic calf developed by Recombinetics which was born without the gene for horns. FDA researchers discovered that the two calves created by the company contained, at the site of the DNA edit, entire antibiotic resistance genes. Photo courtesy of the Cornell Alliance for Science.
Derived originally from the bacterium streptococcus pyogenes, CRISPR-Cas9 is a DNA cutting and targeting system developed in 2012, that can cut and paste nearly any gene into any organism, a scientific breakthrough that opened up new opportunities for cell and organism manipulation.
CRISPR-Cas9 was adapted from a naturally occurring genome editing system in bacteria. The bacteria capture snippets of DNA from invading viruses and use them to create DNA segments known as CRISPR arrays. The CRISPR arrays allow the bacteria to “remember” the viruses (or closely related ones). If the viruses attack again, the bacteria produce RNA segments from the CRISPR arrays to target the viruses’ DNA. The bacteria then use Cas9 or a similar enzyme to cut the DNA apart, which disables the virus.
The CRISPR-Cas9 system works similarly in the lab. Researchers create a small piece of RNA with a short “guide” sequence that attaches (binds) to a specific target sequence of DNA in a genome. The RNA also binds to the Cas9 enzyme. As in bacteria, the modified RNA is used to recognize the DNA sequence, and the Cas9 enzyme cuts the DNA at the targeted location. Although Cas9 is the enzyme that is used most often, other enzymes (for example Cpf1) can also be used. Once the DNA is cut, researchers take advantage of the cell’s own DNA repair machinery to add or delete pieces of genetic material, or to make changes to the DNA by replacing an existing segment with a customized DNA sequence. The whole assembly is often just called CRISPR.
Other gene-editing methods exist (e.g. Zn Finger, TALENs ). However, because of the flexibility of its RNA targeting mechanism, CRISPR, in particular, has been the subject of enormous excitement in the biotech and agricultural research sectors.
CRISPR has mostly been used to create genetic mutations or to insert foreign DNA at desired locations in a genome. Nevertheless, other applications, like gene drives, have also been mooted. Despite the excitement, as Friends of the Earth has summarized, only one gene-edited product, a high oleic oil soybean made by a company called Calyxt, can be found on the market.
For many uses, however, gene-editing with CRISPR is insufficiently precise and a great deal of research is currently oriented towards fixing this defect.
Much of CRISPR’s lack of precision derives from the the fact that, though it is called “editing,” CRISPR and related techniques are really only cutting enzymes. They have no DNA repair function. This means that when repairs are made by the cell to the DNA at the cut site (and the cut must be repaired for the cell to survive) they are largely out of the control of the experimenter. Ten independent editing events will, therefore, give ten different mutations at the same location in the genome.
Thus, at a very basic level, each mutation created at the target site is likely to be unique, even to the extent that DNA from other species may end up being unexpectedly incorporated into the edited genome. To add to this uncertainty, different genome locations, different cell types, different species, and different versions of CRISPR can all influence the kinds of genetic alterations at the target site.
Hope it helps you plzzz Mark my answer as brainlist and follow too....｡◕‿◕｡