What happens after the Cas9 enzyme aligns with the DNA according to the sgRNA?

The Cas9 enzyme plays a crucial role in the CRISPR-Cas9 gene-editing system, acting primarily as a molecular scissors. Once the single guide RNA (sgRNA) guides Cas9 to a specific location on the DNA, the enzyme aligns with the target DNA sequence adjacent to a protospacer adjacent motif (PAM). The correct function that follows this alignment involves Cas9 making a double-strand break in the DNA at that designated site.

This precise cutting is essential for enabling the subsequent repair mechanisms, which can lead to gene editing—either by disrupting a gene or by facilitating the insertion of new genetic material. Thus, the ability of Cas9 to cut DNA at specific locations is what underpins the effectiveness of CRISPR technology in genome editing.