I have to make an exposition in my university about Crispr-cas9 edition and I have some questions about the method. In the knock out/knock in technique is used a plasmid containing the DNA that codifies for the Cas9 protein and guideRNA and a Donor template that has a gene for puromicine resistance, and a DNA that codifies for a fluorescent protein and "left homologous arm" and "right homologous arms". My questions is What's the fuction of the homologous arms?Furthermore what's the role of the Loxp(look at the image)? The method is described here http://www.origene.com/assets/documents/CRISPR-CAS9/CRISPR_manual.pdf (page 5-10)enter image description here

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    $\begingroup$ This is not the CrispR/Cas9 system but the LoxP system which works differently. $\endgroup$
    – Chris
    Commented Sep 25, 2016 at 18:38
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    $\begingroup$ It is there to facilitate homologous recombination and thereby a knock-in. See biology.stackexchange.com/q/29735/3340 $\endgroup$
    Commented Sep 26, 2016 at 5:08
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    $\begingroup$ @ Chris This plasmid can be part of the CRISPR based knock outs, the LoxP sites are there to recycle the marker if you want to do successive knock outs $\endgroup$
    – mimat
    Commented Sep 26, 2016 at 14:02


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