I read this article https://www.quantamagazine.org/20150206-crispr-dna-editor-bacteria/ and am slightly puzzled as to why the CRISPR/Cas 9 system is seen as being so revolutionary. It seems like the very same thing that micro RNA and short interfering RNA does- cleaves synthesised mRNA strands by attaching to the complementary part of the mmRNA strand, and the restrictive enzymes combine to this RNA and cleave it. I don't see how the CRISPR system is any different or better...

Thank you in advance :)

EDIT: Also, does anyone know whether Cas 9 cuts both DNA strands at the same place, or whether it leaves 'sticky ends'? Thank you.

  • $\begingroup$ answer is that CRISPR targets DNA, while siRNA targets RNA. siRNA is incapable of creating mutations $\endgroup$ Commented Nov 28, 2015 at 0:35
  • $\begingroup$ @aaaaaa Thank you for your reply! I see why CRISPR is important in terms of it targeting DNA rather than RNA now! But I was wondering if you could elaborate on siRNA being incapable f creating mutations... From what I understand, CRISPR only cuts DNA at a specific location, and a different system has to be used to insert a new gene section... $\endgroup$
    – Meep
    Commented Nov 28, 2015 at 11:01
  • $\begingroup$ @21joanna12 the CRISPR/Cas9 systems being used commercially and in academics have been cobbled together to cut the DNA and deliver a new template sequence into the cut, not only allowing for sections to be removed, but sections added or mutated as well. That is why it's so revolutionary - it's all based on the gRNA. Just change its sequence, and you change your target. (Hopefully) $\endgroup$
    – MattDMo
    Commented Nov 28, 2015 at 16:57

1 Answer 1


The CRISPR Cas 9 system is used to introduce insertion or deletion in a genomic sequence not mRNA.


  • $\begingroup$ this is not an answer. CRISPR/Cas9 system originally is sort of immune response $\endgroup$ Commented Nov 28, 2015 at 0:34
  • $\begingroup$ @aaaaaa The article that 21joanna12 shows mentions the CRISPR/Cas9 system as a research tool to edit genomic DNA, doesn't it? $\endgroup$
    – 243
    Commented Nov 28, 2015 at 7:00
  • 2
    $\begingroup$ Whatever Cas9 is, it was and is never relevant to the cleaving of RNA, only DNA. This is a perfectly valid answer. $\endgroup$
    – March Ho
    Commented Nov 28, 2015 at 12:43
  • $\begingroup$ this is not high-quality answer $\endgroup$ Commented Nov 30, 2015 at 23:45

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