CRISPR explained: Everything you need to know

Here’s everything you need to know about the complex and sometimes controversial technology driving the gene-editing revolution.

CRISPR evolved as a way for some species of bacteria to defend themselves against viral invaders. Each time they faced a new virus, bacteria would capture snippets of DNA from that virus’ genome and create a copy to store in its own DNA.

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[T]hese snippets of viral DNA were like little books – each one containing the data that allowed the bacterium to recognise and quickly kill off a virus next time it invaded. And in-between these chunks of useful DNA there are slightly less useful chunks of repetitive DNA keeping them separate – like a kind of molecular bookend.

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The spacer sequence is turned into RNA – a molecule that contains messages from DNA – and hunts down the corresponding piece of viral DNA. Once it finds it, an enzyme attached to the RNA string acts as a pair of biological scissors, cutting the target DNA and rendering the virus harmless.

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Scientists use these basic principles to create their own CRISPR molecules which, as we pointed out above, are short stretches of RNA. All you need to do is open up a stretch of interesting-looking DNA – like the bit that contains the mutation that leads to sickle-cell anaemia – and build the complementary RNA sequence, with DNA-chopping enzyme attached.

Read full, original post: What is CRISPR? The revolutionary gene-editing tech explained