CRISPR/CAS9 and Gene Editing Technology

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR/Cas9) of genetic information are no longer news to the world. Its ability to cut genes and target changes to particular genomes. CRISPR possesses RNA genomes that provide the scripts to match the DNA code in the Genome of the organism. It is common in bacteria as it is used to protect itself from viral DNA by cutting viral DNA. Bacteria uses CRISPR as their immune system against viruses where the organism saves the genome of the virus in their CRISPR Locus and the DNA is used as a template to Syntensize RNA molecules which are similar. The RNA finds the matching DNA and then CAS9 cuts theaway the DNA in the genome affected thereby preventing the virus from completely overcoming the bacteria.

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Gene manipulation and engineering have been for a very long time, as we have been changing the genetic makeup of so many plants and animals and this is common even in a variety of dogs. While genetic code manipulation of the cell of a living thing became a thing in the 1970s, it was a very expensive and not accurate method. In 2012 Dr. Emmanuelle Charpentier and Jenifer Doudna discovered how to hijack bacteria's protective mechanism from viruses to directly edit human, animal, and other living organism genes using CRISPR which has a guide RNA and a CAS9 protein that acts as scissors to cut and edit DNA in organisms. With CRISPR it is easy to edit and change genes with accuracy, speed and precision unlike before. There have been a lot of ways to manipulate and mutate organisms before CRISPR such as Transfections which is the use of chemicals to get DNAs into LAB GROWN CELLs but it had its negatives which was having excessive of the gene being introduced in excess and there is too much expression. There were cases where using modified viruses were used to deliver genes as they stick their genetic material into the DNA of hosts but then this can have its negative sides as the intruduction is not specific. The virus just spreads the gene around the entire genetic makeup of the person and this can be bad if the virus deposited gene starts to show a different expression. The Use of Nucleases such as Zinc Finger Nucleases are another way to cut DNAs but then this effect can change the building block of the entire protein completely. With CRISPR, the guide RNA has a 20 nucleotise that complements the target sequence, guiding the CAS9 to the exact genome where it needs to edit and change. The guide RNA which is synthensized with the CAS9 forms the CRISPR/CAS9 and when they reach the region that matches with the guide RNA, it is inserted between two strands of double helix cutting them apart and then allowing the cells natural repair mechanism to repair the cut DNA. CRISPR uses repair mechanisms such as Non homologous end joining (NHEJ) to join the broken DNA ends together resulting in deletions or Indels which would lead to deleting of the genome. It can also be done by done via Homologous directed Repair where the desired template would be used to repair the break.

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One important contribution of CRISPR to science is agriculture. In the past, to get another breed of a plant, there needs to be mutation which might come with undesired changes and this will also take a lot of time but with CRISPR, there can be targeted changes to the gene, thereby affecting a specific property of the plant and not giving an undesired result. With CRISPR, it is easy to knock out the genes of some plants, so as to be able to identify the functions of each gene. In prrincipal, CRISPR is possible in any plant, but then researches are still done on them such as the creatuion of pest, climate, and disease resistant plants.

Just the same way this is done in Animals as well, thereby improving agricultural animals. Asides from using CAS9, other protein CAS can be used like CAS12a. The proteins are responsible for the cutting of the gene while the guide RNA guides the protein. In humans, there are certain diseases that occur as a result of a change in specific genetic properties in humans such as Sickle Cell Disease, Muscular Dystrophy, and Cystic Fibrosis amongst others, but with CRISPR, this can be treated. In the case of treating Sickle Cell Disease, this can be done Ex vivo where the Gene editing molecule is added into cells taken out of the organism for them to be edited, and then replaced. In the case of in vivo, a virus is used to deliver the gene editor into the organism.

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