Final answer:
Editing a DNA sequence with CRISPR-Cas9 requires the creation of a guide RNA that matches the target sequence to guide the Cas9 enzyme to the specific location for editing.
Step-by-step explanation:
Targeting a DNA sequence for editing by the CRISPR-Cas9 system requires the engineering of a guide RNA (gRNA) which contains a sequence complementary to the target DNA region. The gRNA is part of a complex with the Cas9 nuclease that identifies, attaches to, and introduces a double-stranded break at the precise location in the genome where editing is desired.
This process is facilitated by the engineering of a single guide RNA (sgRNA), which is designed to match the target DNA sequence and guide the Cas9 enzyme to the correct location on the DNA strand for editing.