原始问题：
what is the specific work flow about Crisper/Cas9
- First, the researcher designs a single guide RNA (sgRNA) that is complementary to a specific target sequence in the genome.
- The sgRNA and Cas9 protein are then introduced into the cell via a delivery method such as electroporation, viral transfection or microinjection.
- Once inside the cell, Cas9 binds to and cleaves the target sequence of DNA, creating double-stranded breaks (DSBs).
- The cell’s natural repair mechanisms are then activated, allowing for either non-homologous end joining (NHEJ) or homology-directed repair (HDR).
- In NHEJ, short insertions and deletions (indels) occur at the cut site which can lead to gene knockouts or other mutations in that gene depending on where it is located in its coding region; while with HDR, researchers can introduce specific desired changes into the gene by supplying a DNA template containing those changes during repair of the DSBs .
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