The Crispr System : A Series Of Short Direct Repeats

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CRISPR-Cas9 Introduction The CRISPR system is a series of short direct repeats interspaced between sequences inserted into the genome of the bacteria from past infections from viral or plasmids (1). After the discovery of the CRISPR system in the mid-2000s, the CRISPR (clustered regularly interspersed interspaced palindromic repeats) was larger ignored except by microbiologists until the discovery, in 2005, that the spacer sequences were derived from sense and antisense codons of plasmid and viral origin, and then in 2007, with experimental results from Streptococcus thermophilius supported that the CRISPR-Cas system is used in adaptive immunity in bacteria. Lastly, in 2008, with the discovery that mature CRISPR RNAs (crRNAs) served as guides in complexes with Cas (CRISPR associated) protein to interfere with viral and plasmid in bacterial cells. (1) After the discovery that the system was used by bacteria in this manner, researchers began experimentation with the system as a controlled means to of genomic modification in various biological and biotechnological applications. (1) Results and Discussion CRISPR-Cas System The CRISPR-Cas system (often referred to CRISPR-Cas9) is defined by four functional components for efficient RNA-guided genome modification. These components are Cas9, RNase III, tracrRNA, and pre-crRNA. The first of the functional units is the Cas nuclease (1,2). Cas protein has been shown to have helicase and nuclease activity (1), and is the catalytic
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