Now, a new technique, CRISPR-Cas, offers both precision and the ability to modify the genome text at several places simultaneously.
The genome can be viewed as a kind of musical score.
For the genome, such "notes" emerge from cell survival over many generations in an ever-changing environment.
Likewise, elements of a genetic program protected by a solid coating are better able to invade a variety of cells, and to reproduce as the cell reproduces.
In the course of a first infection, a small fragment of the viral genome – a kind of signature – is copied into the CRISPR genomic island (an extra piece of genome, outside of the parent genome text).
When a descendant of the cell is infected with a virus, the sequence will be compared to the viral genome.
Now scientists have figured out how to replicate the process, enabling humans to edit, with the utmost precision, specific genomes – the holy grail of genetic engineering for nearly 50 years.
Previous techniques were especially arduous if one needed to modify several genes, because the process would need to occur sequentially.
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