CRISPR-Cas9 Technology and Its Applications in Genetic Engineering

Abstract

CRISPR-Cas9 is a programmable genome-editing technology derived from a bacterial adaptive immune system. It uses a guide RNA to direct the Cas9 nuclease to a complementary DNA sequence adjacent to an appropriate protospacer-adjacent motif, where Cas9 can generate a targeted DNA break. Cellular DNA-repair processes can then produce gene disruption or, when an appropriate repair template is supplied, more precise sequence changes. The simplicity and programmability of CRISPR-Cas systems have transformed genetic engineering across basic research, agriculture, biotechnology, and biomedical science. Newer approaches include base editing, prime editing, and improved delivery systems that expand the range of possible genetic modifications. This paper examines nine major aspects of CRISPR-Cas9, including its molecular basis, guide-RNA design, DNA repair, gene knockout, precise editing, agricultural applications, disease research, therapeutic development, and safety and ethical considerations.