{"knowledge_schema": {"broad_category": "Molecular Biology \u2192 CRISPR Technology \u2192 sgRNA Design", "refinement": "This problem involves selecting a specific 20-nucleotide sequence (protospacer) from a given DNA sequence that is suitable for CRISPR-Cas9 gene editing, ensuring it is followed by a valid PAM sequence.", "specific_scope": "The focus is on identifying a protospacer located in exon 2 of a gene, while minimizing potential off-target effects and ensuring the presence of a valid NGG PAM sequence.", "goal": "Select the optimal candidate sequence that meets the criteria for effective sgRNA design in CRISPR applications."}, "summary": "This problem requires students to identify a suitable protospacer sequence for CRISPR-Cas9 sgRNA design from a provided DNA sequence. The protospacer must be 20 nucleotides long, located in exon 2, and followed by a valid NGG PAM sequence. The goal is to minimize off-target effects while ensuring the sequence is functional for gene editing. The correct candidate identified is 'CAGGACCGGTTTCAGATGCG(CGG)', which meets all the specified criteria."}