[Campbell Biology P.409] The CRISPR-Cas9 system can be used for both 'knocking out' a gene a... | Practice Question

The CRISPR-Cas9 system can be used for both 'knocking out' a gene and 'correcting' a defective gene. Which of the following statements accurately distinguishes between these two applications based on the provided text?

  • A: Gene knockout involves introducing a normal DNA template for repair, while gene correction does not.
  • B: Both applications rely on the Cas9 protein cutting the target DNA, but gene correction requires the introduction of a functional DNA segment.
  • C: Gene knockout aims to disable a gene by prompting the DNA repair system to remove random nucleotides, whereas gene correction uses repair enzymes to insert random nucleotides.
  • D: The 'knockout' approach utilizes a guide RNA that is not complementary to the target gene, unlike the gene correction method.

Explanation

The text explains that for gene knockout, the DNA repair system introduces or removes random nucleotides because there's no undamaged DNA template, leading to a non-functional gene. For gene correction, a normal functional gene segment is introduced along with the CRISPR-Cas9 system, allowing repair enzymes to use this segment as a template to fix the defective gene. Both processes start with Cas9 cutting the target DNA directed by guide RNA.