A molecular model of a CRISPR-associated (Cas) protein. CRISPRs (clustered regularly interspaced short palindromic repeats) are segments of repeating prokaryotic DNA involved in the prokaryotic immune system, and have been utilized in scientific research for gene editing. Cas proteins are delivered into a cell, whereby the organism's genome can be cut at specific locations in order to add, disrupt or change a sequence of genes.