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A protein derived from the CRISPR-Cas bacterial immune system that has been co-opted for genome engineering. Uses an RNA molecule as a guide to find a complementary DNA sequence. Once the target DNA is identified, Cas12 cuts both strands. Has been compared to “molecular scissors” or a “genetic scalpel.” In CRISPR immunity, cutting viral DNA prevents it from destroying the host cell. In genome engineering, cutting genomic DNA initiates a repair process that ends up making a change or “edit” to its sequence.
Note that Cpf1 (Cas12a), C2c1 (Cas12b), C2c3 (Cas12c), CasY (Cas12d), CasX (Cas12e), Cas14 (Cas12f), and CasPhi (Cas12j) are all Cas12 family members. Our illustration is based on Cas12a.
Refers to changes to a cell’s gene expression that do not involve altering its DNA code. Instead, the DNA and proteins that hold onto DNA are “tagged” with removable chemical signals. Epigenetic marks tell other proteins how to read the DNA, which parts to ignore, and which parts to transcribe into RNA.
Comparable to sticking a note that says “SKIP” onto a page of a book—a reader will ignore this page, but the book itself has not been changed.
Delivering corrective DNA to human cells as a medical treatment. Certain diseases can be treated or even cured by adding a healthy DNA sequence into the genomes of particular cells. Scientists and doctors typically use a virus to shuttle genes into targeted cells or tissues, where the DNA is incorporated somewhere within the cells’ existing DNA. CRISPR genome editing is sometimes referred to as a gene therapy technique.
Scientists have also formed a version of the guide RNA that consists of a single molecule, the single-guide RNA (sgRNA).
A microscopic organism. Can be single-celled or multicellular, and is sometimes used to refer to viruses, although they are not considered to be alive. Examples include bacteria, yeast, and algae.
An endonuclease cuts in the middle of RNA or DNA, while an exonuclease cuts from the end of the strand. Genome engineering tools like Cas9 are endonucleases.