How CRISPR lets you edit DNA - Andrea M. Henle

Living things are defined by their genes, which act as an instruction manual for cells. Recent advancements in gene editing tools allow scientists to change fundamental features of organisms quickly, engineer drought-resistant crops, prevent infectious outbreaks, and develop cures for genetic diseases. CRISPR is the fastest and cheapest gene editing tool responsible for this new wave of science.

The Natural Origin of CRISPR CRISPR is a natural bacterial immune system that uses short DNA sequences and Cas proteins to defend against viruses. When a virus invades, the Cas proteins capture viral DNA segments and create RNA molecules, which bind to a protein called Cas9. This complex acts as scouts, searching for matches to the virus and destroying its DNA.

Hijacking CRISPR for Gene Editing In 2012, scientists discovered how to repurpose CRISPR from targeting viral DNA to editing any DNA in almost any organism. With the right tools, this natural defense mechanism becomes a precise gene-editing tool capable of altering specific genes.

Scientists design a guide RNA to match the gene they want to edit and attach it to Cas9. The guide RNA directs Cas9 to the target gene, where its molecular scissors snip the DNA. This allows for precise editing of practically any gene in the genome by injecting Cas9 bound with custom guide RNA.

CRISPR Applications CRISPR has diverse applications, from creating malaria-resistant mosquitoes to reprogramming drug-resistant cancer cells. It is also used for studying the genome by observing gene modifications within organisms.

Challenges and Ethical Questions Despite its potential, CRISPR is not flawless and may lead to unintended changes. The long-term implications of CRISPR edits are unpredictable, raising significant ethical concerns about its use in various fields such as labs, farms, hospitals, and global ecosystems.