CRISPR

{{expand}}{{sources needed}}[[File:CRISPR overview.jpg|thumb|right|165px|Graphical overview of CRISPR Cas9 plasmid construction]]{{biology}}
'''Clustered regularly interspaced short palindromic repeats''', or '''CRISPR''', are segments within the prokaryote genome that contain repetitive sequences, each separated by a unique "spacer" sequence. Together with Cas proteins, CRISPR is fundamental for viral immunity of prokaryotes,
and relatively recently has been used for genetic engineering to make exceedingly precise alterations.<ref>http://gizmodo.com/everything-you-need-to-know-about-crispr-the-new-tool-1702114381</ref>

==Prokaryote immune system==
In prokaryotes, CRISPR and the associated Cas9 proteins serve as an immune system. When a bacterium survives an infection by a phage, Cas1 proteins cleave a short sequence of the viral DNA, which is then inserted between the repetitive sequences of the CRISPR locus, becoming a new "spacer" sequence. Whenever an infection of the same type of phage happens again, the stored genetic material is transcribed as crRNA, associating with tracRNA, which links it to the enzyme Cas9. When crRNA recognizes its antisense viral strand, Cas9 cleaves it. Since the viral DNA has been incorporated into the genome, the descendant strain also contains the immunity.

TL:DR If a bacteria is attacked by viruses and it survives, it will take part of the virus' DNA and put it in its own DNA. Now if that virus type comes back, the bacteria can send out special cells to hunt it down using the piece of captured DNA as a mug shot.

==What is it?==
CRISPR was first known as segments of [[prokaryote|prokaryotic]] [[DNA]] that contained short repetitive base sequences. It was first discovered in the late-1980s and 1990s, but there are a lot of unanswered questions about it.<ref name=mestel>[https://www.sciencenews.org/article/crispr-had-life-it-became-gene-editing-tool CRISPR had a life before it became a gene-editing tool: Natural CRISPR systems immunize bacteria from invading viruses, and more] by Rosie Mestel (9:00am, April 5, 2017) ''Science News''.</ref> Initially, scientists did not know what the function of CRISPR was, just that it appeared in a lot of different bacteria and archaea, then in 2007 it was shown that different spacers within the CRISPR gene showed adaptive immunity to bacteriophages (viruses that attack bacteria and archaea).<ref name=mestel/><ref>[https://www.ncbi.nlm.nih.gov/pubmed/17379808 CRISPR provides acquired resistance against viruses in prokaryotes] by R. Barrangou et al. (2007). ''Science'' 315(5819):1709-12. DOI:10.1126/science.1138140</ref> Later, it was discovered that a set of genes located near CRISPR, called Cas, interacted with CRISPR to fight phages.<ref name=mestel/> Basically, the CRISPR gene is used to record attacks by phages and other foreign DNA, and the Cas gene is used to snip the intruder's DNA, thereby disabling it; the CRISPR/Cas system acts as a type of immune system for the bacteria/archaea.<ref name=mestel/>

In 2012, two women, {{wpl|Jennifer Doudna}} and {{wpl|Emmanuelle Charpentier||,}} discovered that CRISPR could be used as a quick way to edit DNA when studying a ''Streptococcus pyogenes'' bacterium.<ref>https://en.m.wikipedia.org/wiki/Jennifer_Doudna#Honors_and_Awards</ref><ref>
https://en.m.wikipedia.org/wiki/Emmanuelle_Charpentier#Awards_and_honors</ref> (a.k.a., the [[bacterium]] that causes strep throat. Who knew those bacteria would actually be useful one day?) They named the tool CRISPR/Cas9.<ref>Cas9 is the [[enzyme]] used in the CRISPR process.</ref>

===Intelligent design jumps the bandwagon===
{{main|Irreducible complexity}}
Some creationists argue that the CRISPR system is way too complex for evolution (*cough* Yeah right *cough*) due to the fact CRISPRs differ among species and therefore evolution is wrong. However, this can easily be scientifically explained by the fact that all CRISPRs may have once been exactly the same, but due to random mutation became slightly different.

==So, how does it work?==
CRISPR is actually a system in some bacteria as a virus defense system.

Virus DNA is placed into a "record" of virus DNA so the bacterium can get rid of the virus faster if it comes back. Proteins can be made to snip out certain DNA to defend the bacterium, and therein lies its usefulness.

==Upcoming effects on society==
This discovery revolutionized gene editing and took the genetics world by storm. Scientists have used it to produce mutated monkeys, glow-in-the-dark plants, and (controversially) edit the genes of non-viable [[human]] [[embryo]]s. It could potentially eliminate many of the popular objections to [[genetically modified food]].<ref>[http://www.businessinsider.com/monsanto-ends-gmo-war-crispr-2016-9 Monsanto may have just ended the war on GMOs], ''Business Insider'', 22-Sept-2016</ref>

Jennifer Doudna and Emmanuelle Charpentier received {{wpl|Jennifer Doudna#Honors and Awards|many awards for their discovery.}} The discovery also proves that '''''women''' '''''can''' do SCIENCE and revolutionize the field!!! (As if it hadn't been proven enough already) Another convenient use is to rebut someone when they say women have not contributed to science.

Did we mention that women can do [[science]]?  'Cause women can totally do science, and stuff.

The effects of CRISPR has worried some who say that we may soon use gene editing to change our own DNA. In China in late 2018 a scientist created life though vitro fertilization. Use of CRISPR in this way constitutes human experimentation as it could cause unforeseeable consequences for the babies.<ref>https://www.biospace.com/article/hubris-and-naivete-behind-the-scenes-of-the-crispr-babies-scandal</ref> Geneticists say that the CRISPR edited babies are at a higher risk for genetic decease since we don't know how well CRISPR was applied in their birth.

Gene drive is a very dangerous technology. It has a great capacity to help or harm.<ref>https://www.economist.com/leaders/2018/11/08/gene-drives-promise-great-gains-and-great-dangers</ref>

==In a nutshell==
{{collapse|''Genetic Engineering Will Change Everything Forever – CRISPR'' ([https://www.youtube.com/channel/UCsXVk37bltHxD1rDPwtNM8Q/''Kurzegesagt''])}}


{{video|youtube|jAhjPd4uNFY}}


{{collapse end}}

{{collapse|''How CRISPR lets you edit DNA - Andrea M. Henle'' ([https://www.youtube.com/user/TEDEducation ''Ted Ed''])}}


{{video|youtube| 6tw_JVz_IEc}}


{{collapse end}}

==See also==
*[[Genetically modified food]]
*[[Genetics]]

==External links==
*{{wpa|CRISPR/Cas Tools}}
*{{wpa|CRISPR interference}}
*{{wpa|CRISPR}}
* [http://www.youtube.com/watch?v=k99bMtg4zRk CRISPR-Cas9] to the tune of "Mister Sandman". Yay A-Capella Science!
* [https://www.livescience.com/58790-crispr-explained.html Live Science on CRISPR]

==References==
{{reflist}}
[[Category:Science]]
[[Category:Biology]]
[[Category:Viruses]]

Categories: Science, Biology, Viruses