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Chopped! Using CRISPR/Cas9 to cut DNA - Student's Guide
Version: 1.0 - Release: May 2022 - © 2022 by miniPCR bio™
Student's Guide
P./15
Genome editing with CRISPR/Cas9
The Cas9 enzyme does not change the DNA sequence; it only cuts, creating a double-strand break
in the DNA. Once the DNA has been cut, the cell's repair mechanisms will work to fix the break.
There are a few ways in which the cell can repair such breaks, but, importantly, scientists can take
advantage of these repair mechanisms to introduce changes to the DNA. The most common DNA
repair process often introduces mutations that can disable a gene. While this might sound like a bad
thing, introducing mutations can help scientists understand a gene's function, or in some cases, even
cure a genetic disease. Scientists can also coax the DNA repair mechanism to introduce specific
changes to the DNA at the repair site. Making directed changes in this way has vast potential for
many applications. For example, scientist could potentially change DNA sequences that lead to
disease to DNA sequences that don't.
Advantages of CRISPR/Cas9
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To summarize, the CRISPR/Cas9 system is a powerful genome editing tool for three main reasons:
• Easily programmable: Scientists can target virtually any DNA sequence by changing the 20
nucleotides in the spacer region of the gRNA.
• Highly specific: Targeting only happens when the spacer region finds a perfectly
complementary DNA match, an event that is unlikely to occur at random.
• Widely adaptable: Because universal base-pairing rules dictate pairing of the spacer region
to its DNA target, the CRISPR/Cas9 system can theoretically be used to target DNA in any
organism.
The discovery of CRISPR/Cas9 and its application to genome editing were huge breakthroughs in
biology. This reliable method of editing genes opens up endless possibilities for solving problems in
basic research, human health, agriculture, and many other applied biotechnology fields.
