In the book of Genesis, Satan tells Eve that “God knows that when you eat from [the tree of knowledge] your eyes will be opened, and you will be like God.” As molecular biology and genetic science discover and elevate human knowledge, scientists find themselves considering compelling ethical questions. CRISPR, or clustered regularly interspaced short palindromic repeats, is one of these methods that demands ethical scrutiny. Throughout the course of human history, innovation and technological advancements provoke these philosophical investigations. And for inventions of great destructive and creative potential, a fundamental question arises which confront both CRISPR and the atom bomb. Is it just for humanity to wield divine power?
On June 28, 2012, CRISPR pioneer Jennifer Doudna and her colleagues published a groundbreaking paper titled “A Programmable Dual RNA-Guided DNA Endonuclease in Adaptive Bacterial Immunity.” Just as Oppenheimer’s atomic bomb started the nuclear arms race, Dr. Doudna recalls how she “remember[s] thinking very clearly… [publishing this paper is] like firing the starting gun at a race.” Despite the extraordinarily dense title, the paper actually revealed revolutionary systems for editing DNA. CRISPR technology’s access to modifying DNA has led to advancements in crop resilience, medical breakthroughs, and anthropological knowledge. Using an enzyme called Cas9 that temporarily separates the 5’ and 3’ strands of DNA similar to the effects of helicase during transcription, scientists can access the nucleobases and match a guide RNA up to the relevant strand. If the guide RNA is complementary, then Cas9 will cut the DNA strand. At this point, the repair mechanisms inherent to cell regulation pounce on the DNA strand in an attempt to repair it. In the repair process, the cell must use an identical DNA strand as a template strand to repair the broken one. But scientists are clever, so at this point, a specially engineered and previously inserted DNA strand becomes the template strand. In Summary the CRISPR process takes advantage of the cell’s repair system by cutting DNA and presenting the cell with the blueprint for how to reconstruct it.
But how does this insertion end up changing our DNA? After all, how can such a tiny difference in DNA affect any biological processes when a single strand of human DNA is six feet long when uncoiled? The answer lies in DNA transcription and translation. After transcription in which a messenger RNA complementary to the template DNA strand is synthesized and processed, the mRNA leaves the nucleus and travels to the cytoplasm where translation occurs. The mRNA is effectively the blueprint for a corresponding amino acid. The mRNA enters a ribosome, where anticodons on tRNA read for the codons on the mRNA. As tRNA carries amino acids into the ribosome’s A site, the right codon-anticodon match will trigger a transfer of the amino acid from the tRNA in the P site to the one in the A site, which shifts over into the P site as its predecessor exits through the E site. The process chugs along until the polypeptide chain is complete, at which point a growth factor terminates the synthesis. Triplets of codons correspond to specific amino acids. As a result, having the right nucleobases and codons in place is crucial for attaining the desired amino acid. Thanks to CRISPR, scientists can now identify weaknesses in present DNA structures and engineer potential solutions by inserting the right DNA instructions.
I think that CRISPR will bear the greatest fruit in the agricultural sector (no pun intended). I think that there aren’t many ethical dilemmas when it comes to engineering more resilient and abundant crops, as few would oppose solving world hunger. However, regarding livestock and poultry, CRISPR could reveal some ethical problems, specifically when the well-being of the animal is sacrificed for more short-term agricultural gain. What do you think? Will CRISPR lead the world into a new era of food security, or will it open a Pandora’s box of moral issues just as the atomic bomb did.
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