Clustered regularly interspaced short palindromic repeats (CRISPR) is a family of DNA direct repeats found in many prokaryotic genomes. It was discovered in bacteria as their (adaptive) immune system against invading viruses. Cas9 is an endonuclease enzyme linked with the CRISPR system in bacteria. Bacteria use the Cas9 enzyme to chop viral DNA sequences by unwinding it and then finding the complementary base pairs to the guide RNA. CRISPR/Cas9 is a modern and powerful molecular biology approach that is widely used in genome engineering (to activate/repress gene expression). It can be used in vivo to cause targeted genome modifications with better efficiency as compared to meganucleases, zinc‐finger nucleases and transcription activator‐like effector nucleases. CRISPR/Cas9 is a simple, reliable, and rapid method for causing gene alterations that open new horizons of gene editing in a variety of living organisms, including humans, for the treatment of several diseases. In this short review, we explored the basic mechanisms underlying its working principles along with some of its current applications in a number of diverse fields.

中文翻译：

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CRISPR/Cas9：大自然给原核生物的礼物和基因组编辑的吉祥工具

成簇的规则间隔短回文重复序列 (CRISPR) 是在许多原核基因组中发现的 DNA 同向重复序列家族。它是在细菌中发现的，是它们针对入侵病毒的（适应性）免疫系统。Cas9 是一种核酸内切酶，与细菌中的 CRISPR 系统相连。细菌使用 Cas9 酶通过解开病毒 DNA 序列来切割病毒 DNA 序列，然后找到与引导 RNA 互补的碱基对。CRISPR/Cas9 是一种现代而强大的分子生物学方法，广泛用于基因组工程（激活/抑制基因表达）。与大范围核酸酶、锌指核酸酶和转录激活因子样效应核酸酶相比，它可以在体内以更高的效率进行靶向基因组修饰。CRISPR/Cas9 是一种简单、可靠、以及引起基因改变的快速方法，为治疗多种疾病的各种生物体（包括人类）开辟了基因编辑的新视野。在这篇简短的评论中，我们探讨了其工作原理背后的基本机制以及其在多个不同领域的一些当前应用。