The first element is a reverse transcriptase enzyme bound to a Cas9 nickase enzyme. 

The second element is a strange of RNA known as prime editing guide RNA (pegRNA). It is a single strand of RNA bases that starts with a sequence that binds to one strand of the target DNA (known as the primer binding site), then contains the RNA template with the desired genetic edit in it, a final guide RNA sequence the binds to the other strand of the target DNA, and a stretch of RNA in-between to allow the molecule to bind to both strands at the same time.

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