[Campbell Biology P.410] The text mentions Jennifer Doudna's ethical concerns regarding CRIS... | Practice Question

The text mentions Jennifer Doudna's ethical concerns regarding CRISPR-Cas9 technology, particularly 'possible effects on genes that are not being targeted.' Considering the various definitions of a gene provided and the mechanism of CRISPR-Cas9, which of the following best explains why off-target effects are a significant ethical concern?

  • A: Off-target effects primarily disrupt non-coding regulatory regions, making genes nonfunctional without changing their sequence.
  • B: CRISPR-Cas9's high efficiency means that even minor off-target cutting can lead to unpredictable changes in essential genes, including those encoding non-polypeptide functional RNAs.
  • C: The system only targets protein-coding sequences, but off-target effects can introduce random mutations that are easily corrected by the cell.
  • D: Ethical concerns are mainly due to the difficulty in delivering the Cas9-guide RNA complex into all target cells effectively, not off-target cutting.

Explanation

The text explicitly states Doudna's concern about 'possible effects on genes that are not being targeted,' and that this is an 'active area of research.' The discussion around the definition of a gene broadening to include functional RNAs like rRNA, tRNA means that off-target cuts in any critical DNA sequence, whether coding for protein or functional RNA, can have severe, unpredictable consequences. The 'high efficiency' of CRISPR-Cas9, while beneficial for its intended purpose, amplifies the risk of unintended modifications elsewhere in the genome.