How Does CRISPR Work?

  • By Michael Rivera
  • Posted 05.23.18
  • NOVA

CRISPR makes gene editing faster, cheaper, and easier than ever before. Here's how.

Running Time: 01:36


How Does CRISPR Work?

Published May 23, 2018

Andre Fenton: CRISPR stands for: clustered, regularly, interspaced, short, palindromic, repeats. That’s why it’s just called “CRISPR”.

First discovered in bacteria, CRISPRs are like bacterial immune systems. They have two key parts: a destroyer protein—like one called CAS 9—and a piece of RNA that matches old viruses that previously infected the bacteria.

If the same virus were to invade again, the RNA would recognize the invader’s DNA, attach itself to its old enemy and its CAS partner would slice the virus’s DNA—destroying it.

A few years ago, some researchers realized they could use CRISPR to edit the genome of any living organism.

Here’s the idea: Say I have a stretch of DNA—maybe a part of a gene—I’d like to change. If I know the sequence of letters there—I can build a CRISPR that carries a matching code.

Once inside the cell—CRISPR will scan the DNA until it finds that exact spot. And when it does, it slices the DNA right there.

Now I have a broken gene…but it turns out, I can now insert a new sequence into the gap, and that makes CRISPR potentially an extremely powerful tool.



Digital Producer
Michael Rivera
Produced, and Directed by
Larry Klein
© WGBH Educational Foundation 2018

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