CRISPR A new tool to genome editing


CRISPR- Is a part of DNA that contains short repetition of the base sequences. These are used as a self defense mechanisms.

Bacteriophage- A virus that enters a bacterium and infects it by reproducing it.

Genome- Is a haploid set of chromosomes in a micro organism.

DNA- Deoxyribonucleic acid found in all living organism, carrying all genetic information

RNA- Ribonucleic acid which acts as a messenger carrying instructions from DNA to make protein.

Hereditary- genetic factors passed on from parents to their offspring.

What is the origin of CRISPR?

CRISPR-Cas9 was found in archaea which is a domain and kingdom of single-celled microorganisms, by a scientist at the University of Alicante in Spain, Francisco Mojica. According to the Broad Institute Mojica characterized CRISPR in 1993, and in 2000 he had found the disparate repeat sequence which means that it had contrasting sequences that repeats, and in 2005 Mojica discovered that the sequence were similar to the genomes of bacteriophage which is a virus that infects and replicates inside of the bacterium. CRISPR is the base sequence that is inserted into the targeted genome. After Francisco Mojica had found CRISPR Alexander Bolotin had found the Cas-9. According to Eric S. Lander Alexander Bolotin was studying Streptococcus thermophilus but then found a rather strange CRISPR locus. It was then discovered that the unusual CRISPR included a large protein which had nuclease activity. Cas9 was found that day, May 2005 and is required for target recognition. The discovery of CRISPR-Cas9 is groundbreaking because the function of CRISPR allows for more possibilities in the field of genetic engineering.

How does CRISPR function?

CRISPR gives the ability to scientist to alter genomes cutting out and inserting desired parts of DNA. CRISPR is the specific sequences that is plugged in while Cas9 targets the specific sequence while and inserts, or replaces the previous sequence. The Broad Institute states that “CRISPR “spacer” sequences are transcribed into short RNA sequences (“CRISPR RNAs” or “crRNA”) capable of guiding the system to matching sequences of DNA. When the target DNA is found, Cas9 – one of the enzymes produced by the CRISPR system – binds to the DNA and cuts it, shutting the targeted gene off.” The CRISPR-Cas9 technology had made some improvements from when it was first found. According to Robert Sanders a scientific writer from the UC Berkeley states that there were major improvements made on the CRISPR-Cas9 technology and achieves a 60 percent success rate in replacing a short stretch of DNA with another strand of DNA. The increase rate of success from the CRISPR-Cas9 has allowed it to revolutionize the human race.

How can this revolutionize the human race?

CRISPR is a newly found system with a Cas9 protein attached to it with possibilities that can transform human life by changing genetic sequences. As stated by Doudna and colleagues at UC Berkeley and UCSF “CRISPR-Cas9 tool and employ it to find cures for genetic diseases and therapies for cancer and neurodegenerative diseases. That effort has already borne fruit in the form of a potential treatment or cure for sickle cell disease,” The finding of CRISPR affects how we approach life with a chance of giving babies traits or curing hereditary disease. The week states that “CRISPR can be used safely and without causing unintended genetic changes….DNA and the effects that CRISPR might have on a person's 20,000 to 25,000 genes, which interact in still-mysterious ways…. At some point, researchers could switch their attention from curing hereditary diseases to editing supposedly desirable traits into a person's DNA, such as high intelligence, tall stature, or blue eyes.” The endless possibilities that CRISPR brings to the table do have some types of limitations and things that cannot be done.

What are the limitations to CRISPR?

CRISPR is not fully developed and is still being figured out how to work with a high success rate. Bioethics professor R. Alta Charo stated that “Of the 86 embryos used — all of which were nonviable — just four manifested the new gene designed to replace the defective one. Worse, there were inexplicable mutations in genes that weren't targeted by the researchers. "The number of unintended effects is precisely why this technique is not appropriate for use in clinical applications." The study of CRISPR has lead us to find out that CRISPR has lead us to find out that many new information on the difficulty of gene editing. “Mutation introduced at non-specific loci with similar, but not identical, homology to the target sites are one of the most important complication of these technologies. These can be difficult to identify and require scanning the genome for mutations at sites with sequence similarity to the gRNA target sequence.”

How will future generations be impacted by CRISPR?

CRISPR could affect the human race in both positive and negative ways; diseases could be cured but on the other hand there are unpredictable effects on gene editing for future generations. David Cyranoski and Sara Reardon from the international weekly journal of science claims that “the genetic changes to embryos, known as germline modification, are heritable, they could have an unpredictable effect on future generations. Researchers have also expressed concerns that any gene-editing research on human embryos could be a slippery slope towards unsafe or unethical uses of the technique.” The unpredictability and treacherous outcomes that can be a result from gene editing. There can also be positives on the usage of CRISPR-Cas9 according to Jay Bennett a writer for the popular mechanics. Jay says that a gene editing was used on a infant girl treating here leukemia with a engineered T-cells. It doesn't end there, Francis Crick from the institute in London wanted to genetically modify a human embryo that can reduce the number of miscarriages in the world. The effect on the future generation is unpredictable with opposing morals, its effect on future generations are unknown.

Works Cited

Bennett, Jay. "11 Crazy Gene-Hacking Things We Can Do with CRISPR." Popular Mechanics. Popular Mechanics, 26 Jan. 2016. Web. 17 Feb. 2017.

"Broad Institute." Questions and Answers about CRISPR | Broad Institute. Broad Institute, n.d. Web. 17 Feb. 2017.

Reardon, Sara, and David Cyranoski. "Chinese scientists genetically modify human embryos." Nature News. Nature Publishing Group, 22 Apr. 2015. Web. 17 Feb. 2017.

Sanders, Robert. "Advance improves cutting and pasting with CRISPR-Cas9 gene editing." Berkeley News. University of California Berkeley, 15 Feb. 2017. Web. 17 Feb. 2017.

"The genetic breakthrough that could change humanity, explained." The Week - All you need to know about everything that matters. The Week, 16 Jan. 2016. Web. 17 Feb. 2017

Yeadon, Ph.D Jim. "Pros and cons of ZNFs, TALENs, and CRISPR/Cas." The Jackson Laboratory. Jackson Laboratory, 04 Mar. 2014. Web. 17 Feb. 2017.

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