**Introduction**

**Chapter 1**

**Provisional chapter**

**Introductory Chapter: Modulating Gene Expression -**

**Introductory Chapter: Modulating Gene Expression -** 

Silencing a gene by deleting it, knocking it down, or simply disabling its function has proven to be a promising tool for understanding the function of the gene and to enable lead optimization during drug development process. In recent times, the two commonly used gene modification methods that have been heavily explored are RNA interference (RNAi) and the

RNA interference (RNAi) is a widely used technology for gene-silencing and has become a critical tool for repression of gene expression which is effectively utilized in various researches. Of late, the mechanism of RNA interference has been well investigated, and undergone vari-

The clustered regularly interspaced short palindromic repeats (CRISPR)-associated Cas9/ gRNA system on the other hand, is a unique, targeted genome-modification technique derived from prokaryotic immune system. The cutting edge research and technology advancements in recent years have enabled the CRISPR-Cas9 system to become a popular tool for introduc-

The two technologies, however, vastly differ in their mode of action. RNAi uses small interfering RNA molecules to deplete target mRNAs by triggering their degradation and silencing the gene. In RNAi, short, double-stranded RNA molecules, called small interfering RNAs (siRNAs), bind to messenger RNAs (mRNAs) that bear complementary sequences, and blocks the translation of protein encoded by the mRNA. On the other hand, CRISPR/Cas9 system also known as "molecular scissors" can introduce precise and targeted change within the genome.

ous levels of optimization for improving its effectiveness and efficiency.

ing heritable, precised, insertions and deletions in the eukaryotic genome.

**1.1. Mechanism of the two prominent gene-silencing technologies**

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

DOI: 10.5772/intechopen.84229

**Abridging the RNAi and CRISPR-Cas9 Technologies**

**Abridging the RNAi and CRISPR-Cas9 Technologies**

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

**1. Gene-silencing technologies over the years**

http://dx.doi.org/10.5772/intechopen.84229

revolutionary CRISPR/Cas9 system.

Aditi Singh

Aditi Singh
