In molecular biology, what revolutionary capability was introduced by the CRISPR-Cas9 genome editing system?
Answer and explanation
Correct answer: D. Precise site-specific RNA-guided DNA sequence modification
- Step 1: CRISPR-Cas9 was adapted from a natural bacterial adaptive immune system against bacteriophages. It uses a synthetic guide RNA to direct the Cas9 endonuclease to cut exact target DNA sequences, enabling unprecedented genetic editing accuracy. Answer: Precise site-specific RNA-guided DNA sequence modification. Why not the others: "Random mutational bombardment via X-rays" describes primitive mid-20th-century radiation breeding techniques, which lacked all precision; "Complete eradication of cellular protein" would instantly kill the cell rather than editing targeted genes within its genome; "Synthetic creation of artificial organs" describes advanced tissue engineering and 3D bioprinting rather than molecular gene editing.
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